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Performance Analysis of Finned-Tube Heat Exchanger Charged with Phase Change Material for Space Cooling
Full text linkThe performance of a latent heat storage unit comprised of phase change material (PCM) enclosed in a finned-tube heat exchanger was evaluated experimentally and theoretically to determine its viability to condition a space during summer. The internal and external design conditions of a typical building were selected and analyzed to determine the type of PCM, and the phase change temperature required for space cooling. Subsequently, a PCM of Plus-ice A17 was selected and charged into a small-scale finned-tube heat exchanger. Extensive measurements were conducted on the PCM heat exchanger at different operating conditions. Meanwhile, a three-dimensional computational fluid dynamics model for the PCM heat exchanger was developed and validated with the experimental measurements and thus simulated. When the airflow velocity increases from 1.3 m/s to 6 m/s, the phase change periods decrease by 25% and 13% for the PCM charging and discharging processes respectively. When the PCM thermal conductivity increases from 1 W/(m·K) to 8 W/(m·K), the phase change periods reduce by 36.3% and 47.7% for the PCM charging and discharging processes respectively. In addition, for the same increased range of PCM thermal conductivity, the charging energy efficiency increases by 16.3%, and the discharging energy ratio drops by 7.1%
Numerical investigation of evaporative cooling strategies on the aero-thermal performance of courtyard buildings in hot-dry climates
Full text linkIn hot and dry urban environments, courtyards help mitigate extreme heat and influence the urban microclimate. These structures not only provide light and private outdoor spaces but also aid in mitigating the urban heat island (UHI) effect through improved airflow and evapotranspiration. Courtyards, being central open-air areas enclosed by buildings, are crucial in creating opportunities for natural ventilation driven by wind and buoyancy-induced forces, thus serving as a microclimatic regulator. This study investigates the role of courtyards in modulating their microclimate and adjacent indoor areas by integrating evaporative cooling strategies to enhance cooling in these spaces. While numerous studies have been conducted on the role of water bodies in evaporative cooling, the aero-thermal impact on adjacent indoor spaces remains less understood. Addressing this gap, the present research explores the effect of an evaporative cooling system on the wind and thermal conditions within a courtyard and examines different natural ventilation modes, namely, single-sided and crossflow ventilation, in indoor spaces. A computational fluid dynamics (CFD) model, validated against wind tunnel experimental data, was employed to simulate various evaporative cooling water spray configurations. The results reveal complex courtyard microclimates with diverse cooling effects influenced by room orientation and floor level. Specifically, in single-sided ventilated courtyards, water sprays significantly improved the indoor thermal environment, with the average temperature across all rooms decreased by 2.06 °C, and humidity increased by 4.29 %. However, in cross-ventilated courtyards, water sprays' cooling and humidifying effects were relatively less effective. This research underscores the potential of evaporative cooling technology in improving the microclimate of courtyards, with practical applications extending to urban design and architecture. By tailoring cooling strategies to specific courtyard configurations, urban planners and architects significantly improve indoor comfort levels and energy efficiency
Toward Sustainable Construction: Optimizing Carbon Emission Reduction in the Building Supply Chain through Game-Theoretic Strategies, Government Subsidies, and Cost-Sharing Contract
Full text linkThe carbon emission reduction (CER) in the construction industry can aid in achieving the international community's carbon neutrality target. However, the low motivation of construction enterprises to reduce carbon emissions and the unsatisfactory effect of CER are still unresolved issues. This study aims to address these issues by constructing a building supply chain (BSC) consisting of a developer and a contractor using government subsidies and cost-sharing contracts. The optimal government subsidy and feedback equilibrium strategies of the BSC are examined using a combination of differential game theory and numerical simulations. The findings demonstrate that (1) Cost-sharing contracts may enhance developer and contractor profits and building CER, goodwill, and demand without relying on government subsidies. (2) When subsidized by the government, each equilibrium strategy meets or exceeds the performance of the centralized model, with the cost-sharing contract having a negligible effect on the enhancement of each equilibrium strategy. (3) Both the game structure and the positioning of construction enterprises in the BSC are connected to the number of government subsidies. The city of Shenzhen, one of China's first low-carbon pilot cities, provides a realistic environment for the simulation analysis, with the Block K residential building in Nanshan District serving as a case study. Furthermore, this work contributes to the body of knowledge by proposing a novel CER model for the BSC using differential game theory. The research provides new insights into the role of government subsidies in shaping profit distribution, game structure, and enterprise positioning. Findings demonstrate the value of cost-sharing contracts in improving CER, goodwill, demand, and profits when implemented collaboratively. This advances the theoretical understanding of incentives and strategies for promoting CER in construction.
Practical applications:
This research highlights the importance of collaborative efforts between the government and the BSC to promote sustainable construction and CER. The study found that government subsidies can be an effective tool to encourage developers and contractors to adopt CER practices. However, relying solely on subsidies is insufficient - collaboration through mechanisms like cost-sharing contracts can further enhance sustainability outcomes when enterprises work together. To facilitate low-carbon construction, the government could provide subsidies for developers' promotional and marketing activities as well as funding for contractors' research and development of sustainable materials and technologies. Financial incentives like tax breaks and preferential lending for potential homebuyers can also accelerate consumer demand. Ultimately, creating a supportive environment where enterprises proactively pursue CER creates a win-win situation - the BSC becomes more sustainable while firms improve their branding and profitability. The insights from this research highlight the need for a multi-pronged approach. Governments play a key role through policy and financial support. Realizing the full potential of sustainable construction also requires active participation from developers, contractors, and consumers. By outlining optimal strategies and incentives, this study provides valuable guidance to construction industry stakeholders seeking to implement CER collaboratively
Conceptualising nature-based solutions: addressing environmental challenges in the city of Amman, Jordan
Full text linkThis article explores the conceptualisation and applicability of nature-based solutions (NBS) in the semi-arid context of Amman, Jordan. Through a Delphi survey, interviews and literature review, it investigates local experts’ views, concluding that NBS are a viable approach, even in context of water scarcity and high urban temperatures. Our results advocate for a paradigm shift towards a balanced relationship between urbanisation and nature, the integration of nature-based thinking into educational systems and continuous development and training for planners and local officers. Cross-sector collaboration, a solid participatory framework, and financial mechanisms for pilot cases are essential for this transformative shift
Security, Privacy and Trust of Distributed Ledgers Technology
Full text linkThe Distributed Ledgers Technology (DLT) Sunyaev [2020] refers to decen- tralized technological infrastructure and protocols that allow all participants in the connected system to access, verify, and store updates in an immutable and traceable way across the whole decentralized system. Blockchain technol- ogy Nakamoto [2009] is a typical example of DLT that can record, validate, and store transactions using cryptographic Cho and Lee [2019] hash signatures. In DLT, each distributed participant, as a ledger, is able to process and verify ev- ery transactional item that can be processed based on a consensus of multiple participants. Unlike the central authority-based ledger systems, which need a central authority to validate the authenticity of transactions recorded in the ledgers, the DLT utilizes cryptography algorithms to automatically access, validate, and record transactions based on a specific consensus algorithm in the decentralized network Miraz and Ali [2018a].
As a typical DLT implementation, the blockchain bundles transactions into ’blocks’ that are ’chained’ together through their respective cryptographic hashes. Blockchain technologies have attracted much attention across indus- tries and sectors, such as cryptocurrencies, supply chains, finance systems, banking systems, etc. Alladi et al. [2019] The DLT has great potential to im- prove the way of governance, instituting, and corporations work by offering a way to securely and efficiently create a tamper-proof record of sensitive ac- tions and activities. In recent, DLT has been widely researched and several distributed ledger solutions have been developed, such as Hyperledger Fabric, Ethereum, Quorum, R3 Corda, etc.
The DLT is based on cryptography algorithms Miraz and Ali [2018b], de- centralization networks Zwitter and Hazenberg [2020], and consensus protocols Wahab and Mehmood [2018], which ensure trust among participants through fair execution of transactions. Data in DLT is structured into chained blocks inherent security properties. Each new block is chained to all the blocks before it using a cryptographic chain in such a way that it is nearly impossible to tam- per with the data stored in the ledger Zhao et al. [2019]. All transactions within the blocks are validated and agreed upon through a consensus mechanism, en- suring that each transaction is correct and true. According to the nature of the DLT, there is no single point of failure, and a single user cannot change the record of transactions. However, DLT based technologies are different with many critical security aspects. In DLT or blockchain, the data is organized by cryptographically connected chained blocks and each new block connects to the blocks chained before it in a cryptographic chain Li et al. [2019b]. In this decentralized system, a single point of failure at each participant cannot change the record of transactions.
This chapter has been divided into three distinct sections. Following is an overview of content covered in each section:
Section 1 explains the evolution of distributed databases into blockchain and DLTs (Distributed Ledger Technologies). It also elaborates the differences be- tween distributed databases, blockchain, and DLTs. After presenting the idea of the CAP theorem Frank et al. [2014], it further elaborates the relationship of three basics pillars of the CAP theorem, viz. 1) Consistency (C), 2) Avail- ability (A), and 3) Partition Tolerance (P). The first section also explains the constraints of DLTs for supporting only two of the three features of the CAP theorem and focuses on the three mechanisms of the POW (Proof of Work) Chepurnoy et al. [2017], PBFT (Practical Byzantine Fault Tolerance)Sukhwani et al. [2017], and TDAG (Transactions-based Directed Acyclic Graph) Yeow et al. [2017] for respectively achieving the AP, CP, and CA. This chapter will introduce the detailed DLT with respect to the CAP theorem along with its associated security and privacy issues. in the DLT
The Main Determinants of External Audit Fees: Theory and Empirical Evidence (2014-2016) from (sectoral sets of) FTSE 250 companies
Full text linkResearch Background -The fundamental focus of this thesis is the External Audit service/function (hereafter, audit, or auditing). In so doing, it examines the main determinants of Audit Fees (AF)within the identified sectoral sets of the FTSE250 and explores relevant theories that underpin AF modelling and those that may help to explain the movements in AF under an era of Mandatory Audit Rotation (MAR). Audit and the trust that it engenders is critical to sound Corporate Governance (CG). Hence the thesis is within the domain of CG. Because knowledge is packaged in theories, the theories that could be relevant to AF modelling were first explored in Objective (OBJ)1 of this thesis, which is partly motivated by the absence of an accepted set of theories that help to explain how AF are determined. While statistical confirming literature, regarding the influence of Non-Corporate Governance Variables (NCGVs) and Corporate Governance Variables (CGVs) on AF in several studies exist, equivalent studies were not identified, which specifically focused on their determination within the FTSE 250 index. Additionally, the thesis considers whether the directions of influence and approximate levels of significance of selected AF determinants within the cases audited by the Big4 in this research exhibit a shared commonality across the Big4 in this thesis. This is a response to the common practice of treating the Big4 audit firms as one homogenous unit. Research Setting - The research focuses on theory and empirical testing. In terms of theory, it is mainly facilitated by Agency Theory (AT) and Stakeholder Theory (ST). However, some theories which were not previously associated with AF also appear to align with some qualitative/quantitative explanations for the behaviour of AF, including in relation to MAR and empirical testing in connection with company size (i.e., Dynamic Capability Theory (DCT) and Knowledge Based Theory (KBT)). Empirical testing is based on 83 FTSE 250 companies and their four sectors for three years (2014-2016). The timeline relates to the years 2014 and 2016, in which the Audit Regulation & Directive (2014) (ARD, 2014) came into force and later took effect; respectively. The index is incredibly significant since it serves as a barometer for measuring the performance of the UK listed market. Research Purpose - The purpose of this research is principally to identify the main determinants of AF in the identified cases and their business sectors within the FTSE 250 companies and to identify /explain associated AF modelling theories due to perceived absence of literature that focuses directly on the latter aspects of AF modelling. It also investigates the appropriateness of treating the Big4 auditors as a homogenous unit, as well as the theories that could explain the likely influence of ARD regulation (MAR) on AF. Research Design, Methodology & Approach - The methodological considerations commence by linking empirically focused set of Objectives (OBJs) 2, 3 & 4 with positivist philosophy and associated ontological, epistemological, and axiological issues. To these objectives, it assigns a deductive approach (mainly based on AT), a research strategy that is fundamentally archival, with the choice of research method as essentially mono-methodical and quantitative. Time (frames) horizons are both cross-sectional and longitudinal. OBJs 1 and 5 are theoretical, qualitative, and inductive in approach and hence interpretivist in philosophy, with associated ontological, epistemological, and axiological issues. Research data were culled from various sources including the annual reports of the identified UK FTSE250 companies themselves, information from different electronic databases and data registered at the Companies House and London Stock Exchange (LSE) in UK, for triangulation. Empirical analyses were enabled by multiple regression equations using Ordinary Least Squares regression (OLS) and implemented using IBM SPSS. Innovatively, the research also considers lagged data in empirical testing and develops unique proxies for AUQ and ACC. It also adopts sector-wise and auditor-wise regressions for relevant companies as well as for the overall identified 83 FTSE 250 companies using unlagged and lagged information. Research Findings - Because this research falls within the domain of CG it maintains a fair balance of qualitative (theoretical) objectives (OBJs1 & 5) and quantitative (empirical) objectives ( 2,3 & 4), and hence the nature of its findings/results. In terms of the qualitative (theoretical) aspects, the main ii findings suggest that AF modelling is principally underpinned by AT and ST (OBJ1), including some other theories (such as DCT, Signalling Theory that help explain the behaviour of AF during MAR (OBJ5). Empirically, results show that all models are highly significant (at 0.1%). OBJ2 indicates that the (primary) NCGV determinants of AF in the identified FTSE250 companies, using non-sector-wise regressions, are size, complexity and business sector factors. In terms of sector-wise regressions, complexity is the most influential determinant with some other factors such as size and auditor factors becoming significant determinants although not consistent across the sectors. The latter outcomes are essentially consistent with some relevant aspects of the seminal AF modelling study(Simunic,1980) and most subsequent studies. OBJ3 compares coefficients of NCGVs in OBJ2 with OBJ3 after addition of CGV (Audit Committee Competence (ACC) and Audit Quality (AUQ) to the regressions. It finds that only the predictive powers of Size, Risk, Complexity and one dummy each of the Location and Auditor variables are significantly enhanced. The indication is that the CGVs are not very impactful on the determinants of AF in the identified cases within the FTSE 250. It may suggest that accounting systems and internal controls in FTSE250 appear to be effective hence any extra investment (in the form of AF premia or) in audit committees beyond the minimum legal requirements (e.g., minimum number of Non-Executive Directors (NEDS)) including financial experience, may not generate commensurate returns in terms of certain variables. Finally, findings regarding OBJ4 do not support the regular practice of considering the Big4 as a homogenous unit in AF modelling based on clients’ characteristics. Research Limitations - Despite all models being highly significant, the research data is exclusively secondary. The dummy variables may not have sufficiently captured the effect of the factors (e.g., business sector) which they represent. The theories that mainly facilitate (AT and ST) the research, suffer from several limitations indicated with the thesis. Research Contribution to Knowledge – This thesis extends existing knowledge and contributes original contribution to AF modelling. These include narrowing of the gap arising from the absence of a generally accepted set of theories that help to explain AF determination and some of which help to explain the behaviour of AF under a MAR era.It reaffirms AT and ST as the main underpinning theories of AF modelling. Secondly, it highlights linkages between some additional theories and AF (e.g., DCT and KBT) which were not indicated in prior studies. Thirdly, it extends empirical knowledge to the primarily influence of NCGVs on AF in the most populated sectoral sets of the FTSE 250 (2014-2016). Fourthly, the lagged regression models contribute original knowledge by enabling statistical representation of real-world considerations relating to the importance of prior year variables on the current year’s AF. Fifthly, the thesis develops original proxies for ACC and AUQ. The indication that there is absence of shared commonality between levels of significance and directions of influence of some AF determinants across the Big4 in this research is unique. Consistent with a prior UK study on Big4 AF premia, the thesis also finds that such AF premia are not always justified by commensurate levels of audit quality. Detailed findings provided within the thesis offer some theoretical and empirical knowledge to stakeholders (e.g., Boards, auditors, audit committees, policy makers or regulators) generally, and within the identified cases within the FTSE250. Originality/Value – To the researchers knowledge, this thesis is the first direct quantitate research into AF in FTSE250 or its four most populated sectors. It is the first in UK, to consider the issue of shared commonality (or not) of the impact of a set of primary NCGVs and CGVs across the Big4 auditors. It develops a diagrammatic conceptual framework linking several aspects of the research. Other aspects of originality include linkage of additional theories to AF modeling, being the first to identify theories which help to explain the behaviour of AF under MAR era, developing new proxies of ACC and AUQ and using lagged data in regression models
An evaluation of service expansion to include patients with heart failure with preserved ejection fraction
Full text linkBackground/Aims
The Central London Community Healthcare Trust West Hertfordshire heart failure service expanded in 2020 to include patients with heart failure with preserved ejection fraction in addition to the patients with heart failure with reduced ejection fraction. The patient population was predicted to double, requiring staff and
service adjustments; this warranted an evaluation to determine if care targets were maintained. This study aimed to evaluate the impact of service expansion on service
referral rates, length of stay in the service and clinical workload.
Methods
A retrospective quantitative evaluation of the service data from October 2020 to April 2021 was undertaken to compare referral rates, length of stay in service and key
workload metrics between patients with heart failure with reduced ejection fraction and those with heart failure with preserved ejection fraction. All referrals to the service with a new diagnosis of heart failure (confirmed by echocardiogram or magnetic resonance imaging) were considered for evaluation. Of 250 eligible referrals, 81 were selected for inclusion using a random sampling method.
Results
The participants with heart failure with preserved ejection fraction had a median length of stay in the service of 17 weeks. The participants with heart failure with reduced
ejection fraction had a statistically significant longer stay of 35.57 weeks (P<0.001) compared to a pre-expansion length of stay of approximately 17 weeks. Workload was
proportional between the two cohorts. Patients with heart failure with preserved ejection fraction were more likely to be reviewed in multidisciplinary teams or by the consultant
community clinic. This group was less likely to attend clinic, where 96.4% of face-to-face reviews took place at home. Telephone reviews occurred at a similar frequency for both cohorts, comprising 50% of follow ups. The heart failure with reduced ejection fraction cohort required more alterations in medication and medication titration, generating additional follow ups.
Conclusions The service expansion to include patients with heart failure with preserved
ejection fraction has had a significant impact on workload, leading to a reduction in the
quality of care for those with heart failure with reduced ejection fraction
Industry 4.0 or Pharma 4.0?
Full text linkThis chapter examines the convergence of Industry 4.0 and Pharma 4.0 in the context of healthcare supply chains. It investigates the potential applications of these industrial revolutions to enhance the flexibility, benefits, challenges, and opportunities of healthcare supply chains. This chapter highlights the application of state-of-the-art technology to create intelligent, adaptable, and personalized supply chain systems for the healthcare and pharmaceutical sectors. The literature on “Pharma Industry 4.0” is reviewed, with a focus on the opportunities for sustainable value creation and pharmaceutical supply chain research. Healthcare supply chain has some serious issues like counterfeit drugs, non-transparent supply chain, unfear track and trace system of medicines and biomedical instruments. The authors identified the potential solutions for these issues with the help of current innovative technologies and practices
Factors affecting intention to adopt Green Building Practices: A Journey towards meeting Sustainable Goals
Full text linkAbstract
Purpose
The construction industry and its activities harmfully affect the environment. Hence, adopting green building (GRB) practices can be helpful in achieving sustainable development goals. Therefore, this study aims to identify the factors affecting the intention to adopt GRB practices by extending theory of planned behavior (TPB).
Design/methodology/approach
Using non-probability purposive sampling technique, data was gathered from consultant and contractor engineers in the construction industry through a questionnaire. The analysis was done using partial least square-structural equation modeling technique on a useful sample of 290.
Findings
Findings revealed that the core constructs of TPB [i.e. attitude (AT), subjective norms (SUBN) and perceived behavioral control (PBC)] significantly affect the intention to adopt GRB practices. Moreover, government support and knowledge of green practices (KNGP) were found to be critical influencing factors on AT, SUBNs and PBC. Lastly, the findings confirmed that environmental concerns (ENC) play as a moderating between SUBN and intention to adopt GRB practices, as well as AT and intention to adopt GRB practices.
Practical implications
This study contributes to existing knowledge on GRB, offering evidence base for policy choices regarding climate change adaptation and mitigation in the construction industry.
Originality/value
This study provides insights from the perspective of a developing economy and confirms the applicability of TPB in the adoption of GRB practices. Moreover, this study confirms the moderation role of ENC in between TPB constructs and intention to GRB that is not tested earlier in the context of GRB. This study also confirms that government sustainable support positively affects PBC, and KNGP significantly affects SUBNs
Stock Market and Inequality Distributions – Evidence from the BRICS and G7 Countries
Full text linkBy examining the effects of three stock market indicators (market accessibility, efficiency, and stability) on income and wealth inequality in the BRICS and G7 countries, this study enriches lacking literature on income and wealth inequality, particularly for the BRICS countries. We apply the Autoregressive Distributed Lag–Mixed Data Sampling (ADL-MIDAS) model. We find that only enhancements in market stability reduce income inequality in the BRICS and G7 countries. Additionally, we find that while expansions of market accessibility contribute to narrowing wealth inequality, improvements in market stability widen the wealth disparity in the BRICS countries. Limited effects of the stock market indicators on wealth distribution are observed in the G7 countries