• Technical potential of floating photovoltaic systems on artificial water bodies in Brazil

      Campos Lopes, Mariana Padilha; Nogueira, Tainan; Leandro Santos, Alberto José; Castelo Branco, David; Pouran, Hamid (Elsevier, 2021-09-30)
      Floating photovoltaic systems (FPVs) are an emerging technology where photovoltaic solar panels are placed on the water surface. They are cost-competitive compared to ground-mounted solar farms and provide some additional and unique properties including reduced evaporation of the water from the reservoir, mitigating algae growth; higher efficiency of electricity generation compared to common PV systems because of the cooling effects of water and preventing land-use conflicts. Despite the growing interest in this technology and the opportunities that it could create, there is no systematic assessment of the technical potential of FPVs in Brazil. This work is the first study on the technical potential of FPVs in artificial water bodies applied to Brazil at country and state levels. The country's potential for this purpose was determined based on two criteria: selecting only artificial/man-made water bodies and excluding protected areas. The QGIS software was used to locate water bodies and cross georeferenced meteorological data. The results show that even if FPVs cover only 1% of the identified suitable areas this technology can produce energy equivalent to almost 12.5% of the current national electricity generation and correspond to approximately 16% of Brazil's electricity consumption.
    • The top 10 research priorities in diabetes and pregnancy according to women, support networks and healthcare professionals

      Ayman, G; Strachan, JA; McLennan, N; Malouf, R; Lowe-Zinola, J; Magdi, F; Roberts, N; Alderdice, F; Berneantu, I; Breslin, N; et al. (Wiley, 2021-05-05)
      Aims: To undertake a Priority Setting Partnership (PSP) to establish priorities for future research in diabetes and pregnancy, according to women with experience of pregnancy, and planning pregnancy, with any type of diabetes, their support networks and healthcare professionals. Methods: The PSP used established James Lind Alliance (JLA) methodology working with women and their support networks and healthcare professionals UK-wide. Unanswered questions about the time before, during or after pregnancy with any type of diabetes were identified using an online survey and broad-level literature search. A second survey identified a shortlist of questions for final prioritisation at an online consensus development workshop. Results: There were 466 responses (32% healthcare professionals) to the initial survey, with 1161 questions, which were aggregated into 60 unanswered questions. There were 614 responses (20% healthcare professionals) to the second survey and 18 questions shortlisted for ranking at the workshop. The top 10 questions were: diabetes technology, the best test for diabetes during pregnancy, diet and lifestyle interventions for diabetes management during pregnancy, emotional and well-being needs of women with diabetes pre- to post-pregnancy, safe full-term birth, post-natal care and support needs of women, diagnosis and management late in pregnancy, prevention of other types of diabetes in women with gestational diabetes, women's labour and birth experiences and choices and improving planning pregnancy. Conclusions: These research priorities provide guidance for research funders and researchers to target research in diabetes and pregnancy that will achieve greatest value and impact.
    • Fused deposition modelling: Current status, methodology, applications and future prospects

      Cano-Vicent, Alba; Tambuwala, Murtaza M; Hassan, Sk Sarif; Barh, Debmalya; Aljabali, Alaa AA; Birkett, Martin; Arjunan, Arun; Serrano-Aroca, Ángel (Elsevier, 2021-10-02)
      Fused deposition modelling (FDM) is an advanced 3D printing technique for the manufacture of plastic materials. The ease of use, prototyping accuracy and low cost makes it a widely used additive manufacturing technique. FDM creates 3D structures through the layer-by-layer melt-extrusion of a plastic filament. The production of a printed structure involves the generation of a digital design of the model by 3D design software and its execution by the printer until the complete model is reproduced. This review presents the current status of FDM, how to handle and operate FDM printers, industry standards of printing, the types of filaments that can be used, the post-processing treatments, advantages, and limitations as well as an overview of the increasing application fields of FDM technology. The application areas of FDM are endless, including biomedicine, construction, automotive, aerospace, acoustics, textiles, and occupational therapy amongst others. Even during the current Coronavirus disease (COVID-19) pandemic, FDM has helped to fabricate face masks, ventilators and respiratory systems, respiratory valves, and nasopharyngeal swabs for COVID-19 diagnosis. FDM 3D and 4D printing can produce polymeric and composite structures of various designs, and compositions in a range of materials according to the desired application. The review concludes by discussing the future prospects for FDM.
    • Mixture of piperazine and potassium carbonate to absorb CO2 in the packed column: Modelling study

      N.Borhani, Tohid; Babamohammadi, Shervan; Khallaghi, Navid; Zhang, Zhein (Elsevier, 2021-09-27)
      A rate-based non-equilibrium model is developed for CO2 absorption with the mixture of piperazine and potassium carbonate solution. The model is based on the mass and heat transfer between the liquid and the gas phases on each packed column segment. The thermodynamic equilibrium assumption (physical equilibrium) is considered only at the gas–liquid interface and chemical equilibrium is assumed in the liquid phase bulk. The calculated mass transfer coefficient from available correlations is corrected by the enhancement factor to account for the chemical reactions in the system. The Extended-UNIQUAC model is used to calculate the non-idealities related to the liquid phase, and the Soave-Redlich-Kwong (SRK) equation of state is used for the gas phase calculations. The thermodynamic analysis is also performed in this study. The enhancement factor is used to represent the effect of chemical reactions of the piperazine promoted potassium carbonate solution, which has not been considered given the rigorous electrolyte thermodynamics in the absorber. The developed model showed good agreement with the experimental data and similar studies in the literature.
    • Bone mineral density in high-level endurance runners: Part B—genotype-dependent characteristics

      Herbert, AJ; Williams, AG; Lockey, SJ; Erskine, RM; Sale, C; Hennis, PJ; Day, SH; Stebbings, GK (Springer, 2021-09-22)
      Purpose: Inter-individual variability in bone mineral density (BMD) exists within and between endurance runners and non-athletes, probably in part due to differing genetic profiles. Certainty is lacking, however, regarding which genetic variants may contribute to BMD in endurance runners and if specific genotypes are sensitive to environmental factors, such as mechanical loading via training. Method: Ten single-nucleotide polymorphisms (SNPs) were identified from previous genome-wide and/or candidate gene association studies that have a functional effect on bone physiology. The aims of this study were to investigate (1) associations between genotype at those 10 SNPs and bone phenotypes in high-level endurance runners, and (2) interactions between genotype and athlete status on bone phenotypes. Results: Female runners with P2RX7 rs3751143 AA genotype had 4% higher total-body BMD and 5% higher leg BMD than AC + CC genotypes. Male runners with WNT16 rs3801387 AA genotype had 14% lower lumbar spine BMD than AA genotype non-athletes, whilst AG + GG genotype runners also had 5% higher leg BMD than AG + GG genotype non-athletes. Conclusion: We report novel associations between P2RX7 rs3751143 genotype and BMD in female runners, whilst differences in BMD between male runners and non-athletes with the same WNT16 rs3801387 genotype existed, highlighting a potential genetic interaction with factors common in endurance runners, such as high levels of mechanical loading. These findings contribute to our knowledge of the genetic associations with BMD and improve our understanding of why some runners have lower BMD than others.
    • Bone mineral density in high-level endurance runners: part A—site-specific characteristics

      Herbert, AJ; Williams, AG; Lockey, SJ; Erskine, RM; Sale, C; Hennis, PJ; Day, SH; Stebbings, GK; School of Health Sciences, Birmingham City University, Birmingham, UK. adam.herbert@bcu.ac.uk. (Springer, 2021-09-12)
      Purpose: Physical activity, particularly mechanical loading that results in high-peak force and is multi-directional in nature, increases bone mineral density (BMD). In athletes such as endurance runners, this association is more complex due to other factors such as low energy availability and menstrual dysfunction. Moreover, many studies of athletes have used small sample sizes and/or athletes of varying abilities, making it difficult to compare BMD phenotypes between studies. Method: The primary aim of this study was to compare dual-energy X-ray absorptiometry (DXA) derived bone phenotypes of high-level endurance runners (58 women and 45 men) to non-athletes (60 women and 52 men). Our secondary aim was to examine the influence of menstrual irregularities and sporting activity completed during childhood on these bone phenotypes. Results: Female runners had higher leg (4%) but not total body or lumbar spine BMD than female non-athletes. Male runners had lower lumbar spine (9%) but similar total and leg BMD compared to male non-athletes, suggesting that high levels of site-specific mechanical loading was advantageous for BMD in females only and a potential presence of reduced energy availability in males. Menstrual status in females and the number of sports completed in childhood in males and females had no influence on bone phenotypes within the runners. Conclusion: Given the large variability in BMD in runners and non-athletes, other factors such as variation in genetic make-up alongside mechanical loading probably influence BMD across the adult lifespan.
    • Critical success factors (CSFs) for motivating end-user stakeholder’s support for ensuring sustainability of PPP projects in Nigerian host communities

      Toriola-Coker, L; Owolabi, H; Alaka, H; Bello, WA; Pathirage, C; Pathirage (Emerald, 2021-09-06)
      Purpose: This study aims to investigate two public private partnership (PPP) road projects in Nigeria for exploring factors that can motivate end-user stakeholders for contributing towards sustaining a PPP project in the long-term. Design/methodology/approach: Using a case study methodology approach, this study adopts two-way data collection strategies via in-depth interviews with PPP experts and end-user stakeholders in Nigeria host communities and a questionnaire survey to relevant stakeholders. Findings: The study identifies an eight-factor structure indicating critical success factors for ensuring end-user stakeholders support PPP projects on a long-term basis in their host communities. Originality/value: Results of the study have huge implications for policymakers and project companies by encouraging the early integration of far-sighted measures that will promote long-term support and sustainability for PPP projects amongst the end-user stakeholders.
    • Adaptive fuzzy-logic traffic control approach based on volunteer IoT agent mechanism

      Hewei, Guan; Sadiq, Ali Safaa; Tahir, Mohammed Adam; Vhatkar, Sangeeta (Springer, 2021-12-31)
      Traffic congestion is an extremely common phenomenal issue, it oc-curs in many cities around the world, especially in those cities with high car own-ership. Traffic congestion not only causes air pollution and fuel wastage, but it also leads to an increased commuting time and reduces the work time availability. Due to these reasons, traffic congestion needs to be controlled and reduced. The traffic light is the most widely adopted method to control traffic, however, most traffic lights in use are designed based on the predefined interval, which cannot cope with traffic volume change very well. Therefore, Internet of Things (IoT) based traffic light or adaptive traffic light systems are developed in the recent years as a complement of the traditional traffic lights. The adaptive traffic light can be built based on monitoring current traffic situation or using Vehicle-to-Vehicle and Vehicle-to-Infrastructure communication. This paper proposes a new design of adaptive traffic light, this traffic light system is based on fuzzy logic, and it introduces for the first time the use of volunteer IoT agent mecha-nism, which introduces more accurate results. To note that the presented work in this paper is the extended version of the work presented in (Hewei, G., Sadiq, A.S. and Tahir, M.A. 2021)
    • Three’s Company: discovery of a third syntype of Stegonotus lividus, a species of colubrid snake from Pulau Semau, Lesser Sunda Islands, Indonesia, with comments on an unpublished 19th Century manuscript by the naturalist Salomon Müller

      Kaiser, Hinrich; Mecke, Sven; Kaiser, Christine; O'Shea, Mark (Magnolia Press, 2021-09-14)
      We report on the discovery of a third, male specimen of Stegonotus lividus in the collection of the Muséum National d’Histoire Naturelle in Paris, France, and demonstrate that it is not only a member of the original type series but the only one of the three syntypes, whose morphology was detailed in the original description. We herein identify it as a paralectotype. In their description of S. lividus, Duméril et al. (1854) attributed authorship of the name to the German zoologist Salomon Müller, whose work was never published. By the rules of zoological nomenclature, author attribution solely via an unpublished manuscript is inadmissible, and the species is therefore properly listed as Stegonotus lividus (Duméril et al., 1854). The recent discovery of Müller’s handwritten manuscript, along with an unpublished drawing of one of these snakes by the Dutch artist Pieter van Oort, allows a better assessment of color and pattern for a species that remains known from only three preserved vouchers, as well as improved differentiation from other taxa occurring in the Lesser Sundas and Moluccas.
    • A new species of Stegonotus (Serpentes: Colubridae) from the remnant coastal forests of southern Timor-Leste

      Kaiser, Hinrich; Kaiser, Christine; Mecke, Sven; O’Shea, Mark (Magnolia Press, 2021-09-02)
      During the first amphibian and reptile survey of Timor-Leste, we discovered a population of groundsnakes, genus Stegonotus, in the last remnant of lowland coastal forest along the country's southern coast, which represents a new species. This sexually dimorphic species can be differentiated from all other Wallacean Stegonotus by a combination of 17-17-15 dorsals, ventrals (female 206; males 197-207), paired subcaudals (female 61; males 71-75), the "gull wing +" condition of the rostral, large squared prefrontals that each are 2.5 times the area of the internasals and two-thirds the size of the frontal, a snout-scale ratio of near 0.4 and a frontal-parietal suture ratio of ≤ 1.0, a labial scale formula of 73+4 | 94, five gulars separating the posterior genial and the anteriormost ventral, and an overall brown body coloration that lightens progressively from the vertebral scale row in a dorsal-lateral direction and features color gradients of dark brown posterior edges to lighter brown anterior edges on individual scales. The species is most similar in overall morphology to S. modestus from the central Moluccas and to S. lividus, a species known only from tiny Semau Island that lies off the western end of Timor Island, in close proximity to Kupang, the capital of the Indonesian province of East Nusa Tenggara.
    • Pseudoconservative dynamics of coupled polariton condensates

      Chestnov, I; Rubo, YG; Nalitov, A; Kavokin, A; Nalitov (American Physical Society, 2021-08-24)
      Open-dissipative systems obeying parity-time (PT) symmetry are capable of demonstrating oscillatory dynamics akin to the conservative systems. In contrast to limit cycle solutions characteristic of nonlinear systems, the PT-symmetric oscillations form a continuum of nonisolated orbits. However, precise sculpturing of the real potential and the gain-loss spatial profiles required for establishing of the PT symmetry is practically challenging. The optical devices, such as lasers, exhibit relaxation dynamics and do not operate as the PT-symmetric systems. Here we demonstrate how these constraints can be overcome. We predict that a pair of optically trapped polariton condensates (a polariton dimer) can be excited and operated in the oscillating regime typical of the isolated systems. This regime can be realized in the presence of both dissipative and conservative coupling between the condensates and can be maintained at an arbitrary external pump intensity. Every orbit is characterized by a frequency comb appearing in the spectrum of a dimer in the presence of the conservative nonlinearity. Our results pave the way for the creation of the optical computing devices operating under the constant-wave external pumping.
    • Changing the maps of urban bat distribution

      Hughes, Morgan; Brown, Scott; Maddock, Simon; Young, Christopher; Wiffen,, T; Worledge, L (Bat Conservation Trust, 2021-07)
      Over three decades after the establishment of the Birmingham and Black Country Bat Group, the results of just a few years of targeted advanced surveys at woodland sites in the green belt of the county have begun to challenge the misconceptions of bat assemblages in urban areas. The data from the Urban Bat Project have altered the distribution maps of species previously thought to be 'rare', 'very rare' or 'locally extinct' in the county. The rediscovery of Brandt's bat Myotis brandti and the re-assessment of the rarity scores of nine of the remaining 11 extant county species is likely not due to a legitimate increase in their numbers or a broadening of their distribution. It is, rather, attributable to the increase in recent years of higher quality acoustic monitoring devices and also to a concerted increase in the recording of cryptic and non-ubiquitous species in a previously under-studied and under-valued landscape.
    • Conceptual framework for lean construction ambidexterity in project-based organizations

      Fang, Yanqing; Daniel, Emmanuel Itodo; Li, Shuquan (Routledge, 2021-09-28)
      Lean construction (LC) is widely used to eliminate waste in the construction industry. However, few studies have focussed on LC capabilities. In the absence of a theoretical foundation, the equal treatment of inherent rigidity and flexibility has received little attention. This critical literature review answered the following research questions: What is the current understanding of the two characteristics of LC? Is there a theoretical explanation for their relationship? How can LC capabilities be realized in a project-based organization? The results revealed the lack of a clear definition of LC capabilities. The study posits that LC capabilities involve ambidexterity. Ambidexterity embodies the LC philosophy, principles, and methods, with a focus on resolving the paradoxical tensions in LC projects. Ambidexterity was found to be a two-dimensional paradox comprising exploitative and exploratory capabilities. It emphasizes the achievement of a balance between the two capabilities. The proposed model indicates that LC project-based organizations provide the ideal context for the development of ambidexterity. This study uses a paradoxical lens to introduce the notion of LC capabilities as ambidexterity. This research contributes to the current knowledge and future applications of organizational ambidexterity theory to LC capability development. In addition, it will enable practitioners to understand and manage the paradoxical tensions in LC projects. The proposed framework can guide the creation of an ideal LC project-organization environment.
    • Thin Strut CoCr biodegradable polymer biolimus A9-eluting stents versus thicker strut stainless steel biodegradable polymer Biolimus A9-eluting stents: Two-year clinical outcomes

      Menown, IBA; Mamas, MA; Cotton, JM; Hildick-Smith, D; Eberli, FR; Leibundgut, G; Tresukosol, D; MacAya, C; Copt, S; Slama, SS; et al. (Hindawi, 2021-04-01)
      Background. While thinner struts are associated with improved clinical outcomes in bare-metal stents (BMS), reducing strut thickness may affect drug delivery from drug-eluting stents (DES) and there are limited data comparing otherwise similar thin and thick strut DES. We assessed 2-year outcomes of patients treated with a thin strut (84-88um) cobalt-chromium, biodegradable polymer, Biolimus A9-eluting stent (CoCr-BP-BES) and compared these to patients treated with a stainless steel, biodegradable polymer, Biolimus A9-eluting stent (SS-BP-BES). Methods. In total, 1257 patients were studied: 400 patients from 12 centres receiving ≥1 CoCr-BP-BES in the prospective Biomatrix Alpha registry underwent prespecified comparison with 857 patients who received ≥1 Biomatrix Flex SS-BP-BES in the LEADERS study (historical control). The primary outcome was major adverse cardiac events (MACE)-cardiac death, myocardial infarction (MI), or clinically driven target vessel revascularization (cd-TVR). Propensity analysis was used to adjust for differences in baseline variables and a landmark analysis at day-3 to account for differences in periprocedural MI definitions. Results. MACE at 2 years occurred in 6.65% CoCr-BP-BES versus 13.23% SS-BP-BES groups (unadjusted HR 0.48 [0.31-0.73]; P = 0.0005). Following propensity analysis, 2-year adjusted MACE rates were 7.4% versus 13.3% (HR 0.53 [0.35-0.79]; P = 0.004). Definite or probable stent thrombosis, adjudicated using identical criteria in both studies, occurred less frequently with CoCr-BP-BES (1.12% vs. 3.22%; adjusted HR 0.32 [0.11-0.9]; P = 0.034). In day-3 landmark analysis, the difference in 2-year MACE was no longer significant but there was a lower patient-orientated composite endpoint (11.7% vs. 18.4%; HR 0.6 [0.43-0.83]; P = 0.006) and a trend to lower target vessel failure (5.8% vs. 9.1%; HR 0.63 [0.4-1.00]; P = 0.078). Conclusion. At 2-year follow-up, propensity-adjusted analysis showed the thin strut (84-88um) Biomatrix Alpha CoCr-BP-BES was associated with improved clinical outcomes compared with the thicker strut (114-120um) Biomatrix Flex SSBP- BES.
    • Comparative assessment of predictive performance of PRECISE-DAPT, CRUSADE, and ACUITY scores in risk stratifying 30-day bleeding events

      Kawashima, H; Gao, C; Takahashi, K; Tomaniak, M; Ono, M; Hara, H; Wang, R; Chichareon, P; Suryapranata, H; Walsh, S; et al. (Georg Thieme Verlag, 2020-06-22)
      Background The utility of the PRECISE-DAPT score in predicting short-term major bleeding, either alone, or in comparison with the CRUSADE and ACUITY scores, has not been investigated. This analysis compared the predictive performances of the three bleeding scores in stratifying the risk of 30-day major bleeding postpercutaneous coronary intervention in patients with dual-antiplatelet therapy. Methods In this post hoc subanalysis of the GLOBAL LEADERS trial, the primary safety objective (bleeding according to the Bleeding Academic Research Consortium [BARC] criteria [type 3 or 5]) was assessed at 30 days according to the three scores in the overall population, and in patients with acute (ACS) and chronic coronary syndrome (CCS). Results In a total of 15,968 patients, we calculated all three scores in 14,709 (92.1%). Irrespective of clinical presentation, the PRECISE-DAPT (c-statistics: 0.648, 0.653, and 0.641, respectively), CRUSADE (c-statistics: 0.641, 0.639, and 0.644, respectively), and ACUITY (c-statistics: 0.633, 0.638, and 0.623, respectively) scores were no significant between-score differences in discriminatory performance for BARC 3 or 5 bleeding up to 30 days, and similarly the PRECISE-DAPT score had a comparable discriminative capacity according to the integrated discrimination improvement when compared with the other scores. In ACS, the CRUSADE score had a poor calibration ability (Hosmer-Lemeshow goodness-of-fit [GOF] chi-square = 15.561, p = 0.049), whereas in CCS, the PRECISE-DAPT score had poor calibration (GOF chi-square = 15.758, p = 0.046). Conclusion The PRECISE-DAPT score might be clinically useful in the overall population and ACS patients for the prediction of short-term major bleeding considering its discriminative and calibration abilities.
    • Adult spontaneous hypoglycaemia: preface

      Gama, Rousseau (AME Publishing Company, 2021)
    • Modeling of carbon dioxide absorption by solution of piperazine and methyldiethanolamine in a rotating packed bed

      Esmaeili, Arash; Tamuzi, Amin; Borhani, Tohid N; Xiang, Yang; Shao, Lei (Elsevier, 2021-09-15)
      CO2 removal by the blended amine solution of piperazine (PZ) and methyldiethanolamine (MDEA) with the various molar concentration ratios in a rotating packed bed (RPB) was modelled using MATLAB linked to Aspen Plus. All the required correlations for the RPB in addition to the mass and energy balances were written in MATLAB while the demanded physical and transport properties were extracted from Aspen Plus. The similar operating conditions and compositions in the reported experiments were used to run the model by the two-film theory for mass transfer as steady state, while the impact of five different parameters on the CO2 absorption efficiency was examined to validate the model. The modeling results are in good agreement with the experimental data for which the average absolute deviation is less than 7.0%. The process analysis revealed that rotational speed and PZ concentration have the most significant effects on CO2 absorption efficiency.
    • How are encyclopedias cited in academic research? Wikipedia, Britannica, Baidu Baike, and Scholarpedia

      Li, Xuemei; Thelwall, Mike; Mohammadi, Ehsan (Ediciones Profesionales de la Informacion SL, 2021-09-09)
      <jats:p>Encyclopedias are sometimes cited by scholarly publications, despite concerns about their credibility as sources for academic information. This study investigates trends from 2002 to 2020 in citing two crowdsourced and two expert-based encyclopedias to investigate whether they fit differently into the research landscape: Wikipedia, Britannica, Baidu Baike, and Scholarpedia. This is the first systematic comparison of the uptake of four major encyclopedias within academic research. Scopus searches were used to count the number of documents citing the four encyclopedias in each year. Wikipedia was by far the most cited encyclopedia, with up to 1% of Scopus documents citing it in Computer Science. Citations to Wikipedia increased exponentially until 2010, then slowed down and started to decrease. Both the Britannica and Scholarpedia citation rates were increasing in 2020, however. Disciplinary and national differences include Britannica being popular in Arts and Humanities, Scholarpedia in Neuroscience, and Baidu Baike in Chinese-speaking countries/territories. The results confirm that encyclopedias have minor value for academic research, often for background and definitions, with the most suitable one varying between fields and countries, and with the first evidence that the popularity of crowdsourced encyclopedias may be waning.</jats:p>
    • Mechanical and thermal performance of additively manufactured copper, silver, and copper-silver alloys

      Robinson, John; Arjunan, Arun; Baroutaji, Ahmad; Stanford, Mark (SAGE, 2021-10-08)
      On-demand additive manufacturing (3D printing) offers great potential for the development of functional materials for the next generation of energy-efficient devices. In particular, novel materials suitable for efficient dissipation of localised heat fluxes and non-uniform thermal loads with superior mechanical performance are critical for the accelerated development of future automotive, aerospace, and renewable energy technologies. In this regard this study reports the Laser Powder Bed Fusion (L-PBF) processing of high purity (>99%) copper (Cu), silver (Ag) and novel copper-silver (CuAg) alloys ready for on-demand additive manufacturing (AM). The processed materials were experimentally analysed for their relative density, mechanical and thermal performance using X-ray computed tomography (X-CT), destructive tensile testing and Laser Flash Apparatus (LFA) respectively. It was found that while Ag featured higher failure strains, Cu in comparison showed a 109%, 17% and 59% improvement in yield strength (𝜎𝑦), Youngs Modulus (E) and ultimate tensile strength (UTS) respectively. As such the 𝜎𝑦, E and UTS for L-PBF Cu is comparable to commercially available L-PBF Cu materials. CuAg alloys however significantly outperformed Ag, Cu, and all commercial Cu materials when it came to mechanical performance offering significantly superior performance. The 𝜎𝑦, E and UTS for the novel CuAg composition were 105%, 33% and 94% higher in comparison to Cu. Although slightly different, the trend continued with a 106% and 91% rise for 𝜎𝑦 and UTS respectively for CuAg in comparison to industry-standard Cu. Unfortunately, E values for industry-standard Cu alloys were not available. When it came to thermal performance, L-PBF Ag was found to offer a 70% higher thermal diffusivity in comparison to Cu despite the variation in density and porosity. CuAg alloys however only showed a 0.8% variation in thermal performance despite a 10% to 30% increase in Ag. Overall, the study presents a new understanding regarding the 3D printing and performance of Cu, Ag and CuAg alloys.
    • A systematic literature review evaluating sustainable energy growth in Qatar using the PICO model

      Sarrakh, Redouane; Renukappa, Suresh; Suresh, Subashini; Manu, Emmanuel; Akotia, Julius (Routledge, 2021-03-11)
      With the increasing importance given currently to sustainable development, countries around the world are shifting their focus and efforts to changing the previous unsustainable growth framework. Accordingly, Qatar has decided to introduce a sustainability plan to ensure prosperity through its national vision and strategy plans. In this chapter, a case example has been presented on the application of a systematic literature review according to the PICO model in built environment research based on a study of the efficiency of policies and tactics implemented by the Qatari Government, in its energy sector, pertaining to sustainability strategies. An initial literature search resulted in the identification of 1990 resources within five different databases, of which 82 met the pre-set inclusion and exclusion criteria, including date, geographic location, language, type of publications, participants, and design of studies. The findings showed that six key sustainability initiatives were noteworthy in the Qatar energy sector, which were: health and safety, environment, climate change and energy, economic performance, society, and workforce. The lack of knowledge of the scope of sustainability is a huge challenge for the organisations in the energy sector. The conclusion from this chapter was that the Qatari sustainable development policies still need great efforts to confront their shortcomings, as more holistic policies and more integrated and comprehensive strategies are required.