Adrian Chun Hin Lai and Adrian Wing-Keung Law
Incineration has become increasingly important in many large cities around the world because of fast urbanization and population growth. The benefits of energy production and…
Abstract
Purpose
Incineration has become increasingly important in many large cities around the world because of fast urbanization and population growth. The benefits of energy production and large reduction in the waste volume to landfills also contribute to its growing adaptation for solid waste management for these cities. At the same time, the environmental impact of the pollutant gases emitted from the incineration process is a common concern for various stakeholders which must be properly addressed. To minimize the pollutant gas emission levels, as well as maximize the energy efficiency, it is critically important to optimize the combustion performance of an incinerator freeboard which would require the development of reliable approaches based on computational fluid dynamics (CFD) modeling. A critical task in the CFD modeling of an incinerator furnace requires the specification of waste characteristics along the moving grate as boundary conditions, which is not available in standard CFD packages at present. This study aims to address this gap by developing a numerical incinerator waste bed model.
Design/methodology/approach
A one-dimensional Lagrangian model for the incineration waste bed has been developed, which can be coupled to the furnace CFD model. The changes in bed mass due to drying, pyrolysis, devolatilization and char oxidation are all included in the model. The mass and concentration of gases produced in these processes through reactions are also predicted. The one-dimensional unsteady energy equations of solid and gas phases, which account for the furnace radiation, conduction, convection and heat of reactions, are solved by the control volume method.
Findings
The Lagrangian model is validated by comparing its prediction with the experimental data in the literature. The predicted waste bed height reduction, temperature profile and gas concentration are in reasonable agreement with the observations.
Originality/value
The simplicity and efficiency of the model makes it ideally suitable to be used for coupling with the computational furnace model to be developed in future (so as to optimize incinerator designs).
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Yi Yong Lee, Chin Lay Gan and Tze Wei Liew
The purpose of this paper is to understand the influence of exposure to motivated offenders who may alter the vulnerability levels to phishing victimization. This is particularly…
Abstract
Purpose
The purpose of this paper is to understand the influence of exposure to motivated offenders who may alter the vulnerability levels to phishing victimization. This is particularly focused on explaining the influences of individuals’ online lifestyles and attitudes toward information sharing online on phishing susceptibility.
Design/methodology/approach
This conceptual paper explores the risk of phishing victimization using criminological theories. The authors draw on empirical evidence from existing cybercrime literature and revisit routine activities theory (RAT) and lifestyle RAT (LRAT) to elucidate the risk of phishing victimization. This paper proposes that cyber-RAT, which was developed from RAT and LRAT, could interpret phishing victimization. Grounded on the intervention-based theory against cybercrime phishing, this study suggests that an attitude toward precautionary behavior (information sharing online) is essential to mitigate the phishing victimization risk.
Findings
This paper aims to provide a clear insight into the understanding of phishing victimization risk using theoretical and empirical evidence.
Originality/value
The theoretical perspective outlined provides the understanding of the impacts of online routine activities on a phishing attack which in turn will increase the awareness of phishing threats. The important role of the precautionary countermeasure, that is, attitudes toward information sharing online is highlighted to reconcile the phishing victimization risk.
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George C. Bourantas, Eugenios D. Skouras, Vassilios C. Loukopoulos and George C. Nikiforidis
The purpose of this paper is to make a numerical study of natural convection of water‐based nanofluids in a square cavity when a discrete heat source is embedded on the bottom…
Abstract
Purpose
The purpose of this paper is to make a numerical study of natural convection of water‐based nanofluids in a square cavity when a discrete heat source is embedded on the bottom wall, applying a “nanofluid‐oriented” model for the calculation of the effective thermal conductivity (Xu‐Yu‐Zou‐Xu's model) and the effective dynamic viscosity (Jang‐Lee‐Hwang‐Choi's model). Another motivation is the numerical solution of the equations of the flow with a meshless method.
Design/methodology/approach
A meshless point collocation method with moving least squares (MLS) approximation is used. A test validation study of the numerical method takes place for pure water flow, as well for water/Al2O3 nanofluids. The influence of pertinent parameters such as Rayleigh number (Ra), the non‐uniform nanoparticle size keeping the mean nanoparticle diameter fixed, the volume fraction of nanoparticles and the location of heat source on the cooling performance are studied.
Findings
The presence of a discrete heat source, as well as the various thermal boundary conditions affects the characteristics of the nanofluid flow and heat transfer. When the ratio of minimum to maximum nanoparticle diameter is increased, the local Nusselt number is increased and the heat source temperature is decreased. The increase of solid volume fraction of nanoparticles causes the heat source maximum temperature to decrease and the Nusselt Number to increase.
Originality/value
The present study constitutes an original contribution to the nanofluid flow and heat transfer characteristics when a discrete heat source is presence. “Nanofluid‐oriented” models are used for the calculation of the effective thermal conductivity and dynamic viscosity.
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Ravi K. Perry and Aaron D. Camp
The lived experience of HIV+ Black MSM (men who have sex with men) in the South exposes persistent racialized inequality. With the highest rates of HIV diagnosis in the country…
Abstract
The lived experience of HIV+ Black MSM (men who have sex with men) in the South exposes persistent racialized inequality. With the highest rates of HIV diagnosis in the country, Black MSM are made to feel unequal within the US LGBTQ community, thereby perpetuating long-standing inequalities between the groups. We argue that Whites' and Blacks' differing conceptions of racial equality serve to limit the extent to which comprehensive LGBTQ equality is possible as whiteness frames the LGBTQ experience in the United States. Examining how the country's racist story of nonaccess, representation, and exclusion has stymied coalition building to eliminate inequalities, findings reveal the structural impediments toward racial parity. Utilizing the case study of HIV+ Black MSM in the South, we examine the persistence of inequality amid the thrice interwoven intramarginalization of feeling excluded from sociopolitical spaces, having limited political representation, and engaging with racist body politics.
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Soohyun Park and Hyoung Sun Yoo
This study investigates the effects of related and unrelated technology diversity on R&D efficiency and how a firm’s unique core technology moderates this relationship. In…
Abstract
Purpose
This study investigates the effects of related and unrelated technology diversity on R&D efficiency and how a firm’s unique core technology moderates this relationship. In particular, this study aims to address the research gap in the technological diversity literature by examining whether the effects of related and unrelated technological diversity on R&D efficiency are consistent in the context of R&D-intensive firms.
Design/methodology/approach
Using a panel dataset of 516 top R&D investors worldwide from 2012 to 2018, the paper tests hypotheses on how the ambivalence of technological diversity affects R&D efficiency depending on the level of diversity.
Findings
Unrelated technological diversity has an inverted U-shaped curve relationship with R&D efficiency, which indicates that there exists an optimal point of unrelated technological diversity. Additionally, core technology plays a contingent role in this relationship by alleviating the volatility of the inverted U-shaped relationship between unrelated technological diversity and R&D efficiency.
Originality/value
This study makes an original contribution to the technological diversity literature by adopting an approach not limited to specific countries or industries, focusing on R&D-intensive contexts. Furthermore, the paper distinguishes the various types of technological diversity, considering that the motivations and strategic objectives underlying technological diversity vary depending on the specific type. This allows researchers to gain a deeper insight into how different types of diversity strategies impact R&D efficiency.
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Purpose – Intersections are hazardous locations and to improve their safety we need to understand the factors contributing to crashes at these locations and provide evidence-based…
Abstract
Purpose – Intersections are hazardous locations and to improve their safety we need to understand the factors contributing to crashes at these locations and provide evidence-based recommendations to reduce them. This chapter provides a summary of the findings on infrastructure-related factors contributing to crashes at urban and rural intersections and some discussions on the implications and potential countermeasures.
Approach – A review of the literature on intersection crashes was performed to identify the infrastructure-related crash-contributing factors. Some discussions on the implications and potential countermeasures are then provided.
Findings – The factors contributing to road crashes are diverse and complex. While the safety effects of a few factors (e.g., exposure and speed) are relatively consistent, many factors have different impacts on crash frequency and severity (e.g., types of intersection) and different impacts on urban and rural intersections (e.g., bus stops).
Research Implications – More studies are needed on developing a stronger theoretical or conceptual foundation on the effects of roadway designs and traffic controls on different dimensions of safety (e.g., exposure, frequency, severity, etc.), types of crashes (e.g., head-on, rear-end, etc.) or road users involved (e.g., drivers, pedestrians, cyclists, etc.).
Practical Implications – Transport engineers need to be aware that some treatments may have different effects on different crash types and road users involved. Even though the overall safety may be improved by the treatments designed, they need to consider and mitigate any unintended consequences to satisfy the Pareto improvement principle and the social equity criterion.
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Recep M. Gorguluarslan, Umesh N. Gandhi, Yuyang Song and Seung-Kyum Choi
Methods to optimize lattice structure design, such as ground structure optimization, have been shown to be useful when generating efficient design concepts with complex truss-like…
Abstract
Purpose
Methods to optimize lattice structure design, such as ground structure optimization, have been shown to be useful when generating efficient design concepts with complex truss-like cellular structures. Unfortunately, designs suggested by lattice structure optimization methods are often infeasible because the obtained cross-sectional parameter values cannot be fabricated by additive manufacturing (AM) processes, and it is often very difficult to transform a design proposal into one that can be additively designed. This paper aims to propose an improved, two-phase lattice structure optimization framework that considers manufacturing constraints for the AM process.
Design/methodology/approach
The proposed framework uses a conventional ground structure optimization method in the first phase. In the second phase, the results from the ground structure optimization are modified according to the pre-determined manufacturing constraints using a second optimization procedure. To decrease the computational cost of the optimization process, an efficient gradient-based optimization algorithm, namely, the method of feasible directions (MFDs), is integrated into this framework. The developed framework is applied to three different design examples. The efficacy of the framework is compared to that of existing lattice structure optimization methods.
Findings
The proposed optimization framework provided designs more efficiently and with better performance than the existing optimization methods.
Practical implications
The proposed framework can be used effectively for optimizing complex lattice-based structures.
Originality/value
An improved optimization framework that efficiently considers the AM constraints was reported for the design of lattice-based structures.
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Kyung-Shick Choi, Whitney Sanders and Claire Seungeun Lee
The purpose of this study is twofold: (1) to diagnose and analyze the current state of child sexual violence in the Metaverse through thematic analysis, identifying patterns and…
Abstract
Purpose
The purpose of this study is twofold: (1) to diagnose and analyze the current state of child sexual violence in the Metaverse through thematic analysis, identifying patterns and empirically diagnosing issues and (2) to enhance cybercrime investigation capabilities and public safety training in Metaverse investigations in the future.
Design/methodology/approach
By using thematic analysis, the study examines online child sexual violence victimization cases in the Metaverse, collecting data through keyword searches in newspapers and court records.
Research limitations/implications
This study provides detailed policy recommendations for building trust between the government and citizens involved in the digital age.
Originality/value
The research endeavors harbor a dual focus: first, to meticulously dissect and comprehend the prevalent landscape of child sexual violence within the intricate realms of the Metaverse. Through rigorous thematic analysis, the authors endeavor to unearth underlying patterns, diagnose empirical realities and illuminate the pressing issues at hand. Second, the authors aspire to fortify the arsenal of cybercrime investigation techniques, bolstering the capacity for future Metaverse inquiries. Using thematic analysis, the study meticulously scrutinizes a dozen cases of online child sexual violence, meticulously gathering data from diverse sources such as newspapers and court records. The implications of the research extend far beyond academia, offering concrete policy recommendations to safeguard vulnerable denizens of the Metaverse.
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Stefan Schwarz and Ekkehard Ramm
The present contribution deals with the sensitivity analysis and optimization of structures for path‐dependent structural response. Geometrically as well as materially non‐linear…
Abstract
The present contribution deals with the sensitivity analysis and optimization of structures for path‐dependent structural response. Geometrically as well as materially non‐linear behavior with hardening and softening is taken into account. Prandtl‐Reuss‐plasticity is adopted so that not only the state variables but also their sensitivities are path‐dependent. Because of this the variational direct approach is preferred for the sensitivity analysis. For accuracy reasons the sensitivity analysis has to be consistent with the analysis method evaluating the structural response. The proposed sensitivity analysis as well as its application in structural optimization is demonstrated by several examples.