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Thermodynamic analysis and in situ PXRD study of mineralogy phase transformation of arsenopyrite in acid pressure oxidation
No full textAcid pressure oxidation (POX) is a cost-efficient pre-treatment method for releasing refractory gold from arsenopyrite and pyrite prior to cyanidation. However, ongoing debate surrounds the mechanism of the dissolution, crystallization, and phase transformation during POX, in part due to the lack of thermodynamic data and in situ studies of the acid POX. In this study, we developed Eh-pH diagrams and used in situ powder X-ray diffraction (PXRD) to investigate mineralogical phase changes during acid POX of arsenopyrite. Based on the existing thermodynamic data, we established the Eh-pH diagrams for the Fe-As-S-H2O systems at 225 °C and 100 °C, which correctly predicted the predominant solid phases precipitating during POX of arsenopyrite at a pH range of 0 to 0.5, such as basic ferric sulphate (BFS: Fe(OH)SO4), szomolnokite (FeSO4·H2O), hydronium jarosite ((H3O)Fe3(SO4)2(OH)6) and angelellite (Fe4O3(AsO4)2). FeSO4·H2O solid is the stable phase during annealing stages as predicted by the Eh-pH diagram, which is in line with the observed solid phases using in situ PXRD. The influence of initial concentration of ferric ions and the presence of pyrite on mineral phase change was revealed. Our results confirmed the formation of FeSO4·H2O, BFS and hydronium jarosite during annealing stages, while BFS and/or hydronium jarosite dissolved during curing and cooling process. Especially, the formation of angelellite was observed in the presence of pyrite during cooling process, which is well-agreed with thermodynamic analysis
Identification of fractional Hammerstein model for electrical stimulated muscle: An application of fuzzy-weighted differential evolution
No full textFractional order representations model complex systems with less parameters, improved accuracy and enhanced robustness in control systems but the system identification of fractional order systems is highly complicated and challenging task because of substantial nonlinearity of the input, unknown linear/nonlinear parameters of the blocks, and unknown fractional order. In this paper, parameter estimation technique is proposed based on fuzzy-weighted differential evolution algorithm for fractional electrically stimulated muscle models, which is generalization of fractional Hammerstein controlled autoregressive model vital for rehabilitation of spinal cord injury (SCI) patients. The system identification problem of fractional electrically stimulated muscle models (FESMMs) is formulated via mean square error approximation between the true and estimated response of FESMMs. The parameters of FESMMs are identified by employing fuzzy weighted differential evolution algorithm optimization knacks of with polynomial, cubic spline and sigmoidal input nonlinearities on various noise variances in the system dynamics. Comparison of results from actual to calculated responses indicates closeness up to 4 decimal places of accuracy for FESMM with polynomial type nonlinearity, up to 6 decimal places for FESMM with sigmoidal type kernel, and up to 5 decimal for FESMM with cubic spline type nonlinearity for different low and high signal to noise scenarios i.e., σ2=0.0022,0.022,0.22, which verify the precision, efficacy, stability and reliability of the fuzzy weighted differential evolution algorithm for system identification of FESMMs in rehabilitation scenarios of SCI
Graphene-based phononic crystal lenses: Machine learning-assisted analysis and design
No full textThe advance of artificial intelligence and graphene-based composites brings new vitality into the conventional design of acoustic lenses which suffers from high computation cost and difficulties in achieving precise desired refractive indices. This paper presents an efficient and accurate design methodology for graphene-based gradient-index phononic crystal (GGPC) lenses by combing theoretical formulations and machine learning methods. The GGPC lenses consist of two-dimensional phononic crystals possessing square unit cells with graphene-based composite inclusions. The plane wave expansion method is exploited to obtain the dispersion relations of elastic waves in the structures and then establish the data sets of the effective refractive indices in structures with different volume fractions of graphene fillers in composite materials and filling fractions of inclusions. Based on the database established by the theoretical formulation, genetic programming, a superior machine learning algorithm, is introduced to generate explicit mathematical expressions to predict the effective refractive indices under different structural information. The design of GGPC lenses is conducted with the assistance of the machine learning prediction model, and it will be illustrated by several typical design examples. The proposed design method offers high efficiency, accuracy as well as the ability to achieve inverse design of GGPC lenses, thus significantly facilitating the development of novel phononic crystal lenses and acoustic energy focusing
The Effectiveness and Compliance of Routine Antenatal RhIG Prophylaxis using Different Strategies: A Systematic Review and Meta-analysis
No full textRoutine antenatal anti-D prophylaxis has successfully reduced the incidence of RhD alloimmunisation and Haemolytic Disease of the Foetus and Newborn (HDFN). However, there are different strategies and guidelines available across different countries. This systematic review and meta-analysis aimed to investigate the effectiveness and compliance of routine antenatal prophylaxis of different strategies by measuring detectable anti-D levels at delivery, RhD alloimmunisation rate and compliance. PubMed, SCOPUS, EMBASE and Cochrane Library were searched up until 30 July 2023. Binary random effects meta-analysis using maximum likelihood method was performed in Open Meta Analyst software. 17 studies were eligible for meta-analysis. More women had detectable anti-D at delivery after two-dose regimen (24.5%; estimate 0.532, 95% CI [0.181, 0.866], P<0.001) than one-dose regimen (18.35%; estimate 0.252, 95% CI [0.107, 0.433], P<0.001). The rate of RhD alloimmunisation was higher for two-dose regimen (0.33%; estimate 0.003, 95% CI [0.002, 0.005], P<0.001) when compared to one-dose regimen (0.13%; estimate 0.002, 95% CI [0.000, 0.005], P<0.001). Targeted antenatal Rh Immune Globulin (RhIG) had the highest compliance (90.01%; estimate 0.903, 95% CI [0.880, 0.924], P<0.001). One-dose had higher compliance when compared to two-dose regimens (88.73% vs. 61.49%; P=0.004). Both universal one-dose and two-dose regimens were equally effective for the prevention of RhD alloimmunisation. However, one-dose regimen would perform better than two-dose regimen due to higher compliance. The targeted regimen which uses a single dose of RhIG is considered the best strategy for routine antenatal prophylaxis with the highest compliance
Suitability of Foamed Concrete for the Composite Floor System in Mid-to-High-Rise Modular Buildings: Design, Structural, and Sustainability Perspectives
No full textThis study investigates the application of lightweight foamed concrete (FC) in modular building floor systems to address challenges in lifting and transportation within modular construction. Initially, a literature review identifies FC’s characteristics and optimum mix design, considering its sustainability and strength. The comprehensive review highlights that FC can be a lightweight alternative to replace traditional concrete in floor structures. Further, this study conducted the life cycle assessment and indicates that FC with coarse fly ash substitution is the optimum mix, which releases less greenhouse gas emission (i.e., 740.89 kg CO2-eq/1 m3) than other mixes. Subsequently, the study conducted design verification and parametric study of composite floor systems (i.e., cold-formed steel-FC, timber-FC, and steel deck-FC). The results show similar flexural and shear performance compared to normal-weight concrete despite its lower density (1600 kg/m3) compared to normal-weight concrete (2400 kg/m3). Further, the reduction of modulus of elasticity (43% of normal-weight concrete’s value) in FC increases deflection by 22–46% and 11–15% for steel-FC and timber-FC floor systems, respectively. Overall, the outcome shows that FC can be an efficient alternative for mid-to-high-rise modular building floor construction. Its lightweight nature can reduce the module’s weight, making modular construction more cost-effective
Place branding: Religion in shaping the three-dimensional essence of a city brand through stakeholder engagement
No full textThis study explores the role of religion in engaging stakeholders in branding a place on social media and unmasks what implications this has for (re)constructing the three-dimensional meanings of a place brand. Using the content analysis method to examine the case of Saudi Arabia, it probes how the key stakeholder groups of the government and the residents structure and interact with the narratives of the cities—Jeddah and Riyadh—on Twitter, Facebook, and Instagram. The results show the Islamic religion serves as a powerful tool for motivating the residents to engage in the government-led city branding initiatives at the individual level. However, the strategy of dwelling on religion to mobilize resident engagement at the individual level towards the social level with the aim of growing resources in support of social development should be reassessed within a dynamic social system. Theoretically, the proposed framework of religion city branding expands the scope of stakeholder engagement in place branding research through the integration with the driver of religion, especially unveiling how religious factors shape the personality traits of a place brand. It contributes to the practical sense that religious elements might be deployed by the key stakeholder groups of the government and residents in city branding initiatives, which potentially contributes to their relationship and the engagement of residents in co-creating a place brand with the government. This Saudi-focused study, therefore, possesses significance for place branding practices in Middle Eastern countries and beyond
Enhanced mechanical properties of re-entrant auxetic honeycomb with self-similar inclusion
No full textA new auxetic honeycomb configuration is proposed by adding self-similar inclusion to the conventional re-entrant hexagonal structure. Theoretical models of the elastic mechanical property are developed for both auxetic honeycombs. The new re-entrant honeycomb exhibits enhanced auxeticity and stiffness compared to the original structure. Both experimental and numerical simulation methods are employed to investigate the in-plane compressive behavior of the auxetic structures, and they show good agreement. The dramatic increase in stiffness observed in the stress–strain curve of the novel auxetic structure can be attributed to self-contact during compression, leading to a significant escalation in plateau stress. The specific energy absorption of the new auxetic structure is approximately 10 times greater than that of the original structure. In addition, the new design enhances the stability of compressive deformation, resulting in a more consistent negative Poisson's ratio effect. A parametric study of the inclusion's geometry is also conducted using the validated numerical model, demonstrating that the concave angle of the inclusion is a key parameter to influence the energy absorption capability and compressive stability. Reducing the height-to-length ratio of the entire structure can significantly prevent its buckling. The proposed auxetic honeycomb exhibits significant potential for application in protection engineering, due to its superior stiffness and energy absorption capacity
Authenticity, Social Media Discourse and the Public Literary Self
No full textThis is the first book-length study on how authors of color present themselves in public literary discourse. The book examines data including the case study authors' Twitter usage, and thereby the impact of the digital sphere in author self-presentation
Complex Evolving Systems and Iterative Approach to Solving Complex Problems
No full textThis chapter intends to take the Engineering Management discipline to new higher level that Engineering Managers can meet demands the 21st Century digital economy. It covers a deficit in understanding complexity which is not only glaring but – given the current state of the world - has become patently unacceptable. Furthermore, the chapter is intended to assist higher education in designing new post graduate programs, which covers a deficit in understanding of complex project environment, which ultimately links to two fundamental concepts of complex evolving system and social learning
Engineering Economic Strategy and Problem of Economic Complexity
No full textEngineering Economic Strategy (EES) refers to the effective implementation of a set of strategic steps by an engineering or technology company in specific market conditions and specific geographic places over a time period. EES crosses many disciplinary boundaries. It is a transdisciplinary body of knowledge which facilitates economic development and higher productivity while focusing on improving human conditions via effective engineering solutions, product developments, and connection to services. It consists of three core interrelated disciplines; (1) Engineering Enterprise, (2) Economic Development, and (3) Strategic Focus