240106 research outputs found
Sort by
Uncertainty-driven optimization of photovoltaic-integrated building-level energy Hubs:Advancing SDG 7 targets
No full textThis paper develops a bi-level uncertainty-driven optimization model whose fundamental elements are risk management at the upper level and the techno-economic and environmental assessment at the lower level to enhance the energy efficiency of photovoltaic-integrated building-level energy hubs (BEHs), supporting the goals of Sustainable Development Goal 7. The lower level uses the energy hub tool to model buildings as BEHs, efficiently coordinating energy carriers, conversion technologies, and storage systems. It aims to determine optimal operational schedules that meet various constraints while minimizing operational costs. The upper level applies risk-averse decision-making using information-gap decision theory to handle multiple, interdependent uncertainties over the operational horizon. A hybrid solution approach combines the non-dominated sorting genetic algorithm II at the upper level with the DICOPT solver at the lower level, addressing the model's complex, mixed-integer, and nonlinear structure. A hybrid decision-making tool is developed by integrating the fuzzy satisfying method with the distance metric methodology to identify the optimal solution from the Pareto frontier. The model is validated through cases on an industrial building, demonstrating superior performance over traditional approaches in key performance indicators. Overall, the model offers a robust and scalable method for optimizing energy efficiency in the building sector under simultaneous uncertainties.</p
Reflection of serum PCB concentrations in silicone wristbands, hand wipes, indoor air, and dust and the associations between exposure and thyroid hormone homeostasis
Full text linkPolychlorinated biphenyls (PCBs) are legacy contaminants that are enduring indoor environmental problems due to historical applications. Among residents living in PCB-contaminated and reference apartments, we compared the effectiveness of personal and environmental samples for determining exposure through associations with 14 serum PCBs and explored potential effects on thyroid biomarkers. Silicone wristband PCBs were strongly correlated with serum measurements, particularly for lower chlorinated PCBs (rs=0.59-0.82), and showed for the first time that wristbands are effective indicators of internal dose for PCBs. Similar correlations were observed for indoor air and dust, and hand wipes were significantly associated with serum for all congeners (rs=0.44-0.73). Stratified analyses, which accounted for some participant characteristics, demonstrated that significant relationships were specific to those living in contaminated apartments and most focused among lower chlorinated congeners. Here, residents had lived in their homes for many years (mean>10 years) and spent most of their time at home, due in part to being a majority aging population. As such, the four external exposure measures were strongly inter-correlated across the congeners. We also observed associations with free triiodothyronine (T3) and ratio between T3 and thyroxine (T4) in the exposed population. T3 and PCB-28 shared a significant, inverse dose-response relationship, with 13 and 17% decreases in T3 for the second and third serum PCB-28 tertiles, respectively. Our results suggest that any of the four sample types collected in this exposure scenario accurately pointed to elevated PCB exposure and that this exposure was associated with a change in thyroid hormone homeostasis.</p
Protein distribution in SBA-15:Insights from thermal decomposition and advanced imaging
No full textOrdered Mesoporous Silica (OMS) materials, particularly SBA-15, are widely used in drug delivery due to their structural stability and high porosity. However, the role of macroporosity (pores >50 nm) in influencing protein adsorption and spatial distribution remains poorly understood. In this study, three SBA-15 variants were produced by changing the synthesis temperature and stirring speed, and combined evolved gas analysis (EGA), Raman imaging, and X-ray micro-computed tomography (micro-CT) were used to investigate the adsorption and distribution of lysozyme, a model protein, in the samples. While thermal analysis showed comparable overall protein uptake across all variants, Raman imaging and micro-CT demonstrated that SBA-15 with the larger macropore distribution exhibited a less uniform lysozyme distribution. These observations suggest that macroporosity affects protein localization within SBA-15, which is critical for optimizing antigen delivery and release. Our results advance understanding of how OMS morphology impacts biomolecule encapsulation, offering insights valuable for the design of advanced drug delivery systems and oral vaccines.</p
Experimental investigations of internal macro-scale convection in the loose-fill wood fiber insulation layer of a full-scale wall element
No full textWith increasing restrictions on the energy efficiency of buildings, thicker insulation layers are installed in new and refurbished buildings to reduce heat losses. Previous studies have indicated that internal macro-scale convection cells can occur in thick porous insulation layers, decreasing the thermal performance of the envelope component. The focus of previous studies has been on horizontal insulation layers, most often composed of glass wool. Therefore, there is a lack of empirical data for loose-fill insulation and, in particular, bio-based materials, which have the potential of being more sustainable than conventional ones. The present investigation of this paper looks at the possibility of internal macro-scale convection inside loose-fill wood fiber insulation in a full-scale vertical wall element, with the modified Rayleigh number in the current investigation being between 20 and 45 and exhibiting internal convection in all cases. The experimental results show good agreement in terms of heat flux and temperature distribution with numerical simulations where the macro-scale convection is modelled explicitly. It also indicates that internal macro-scale convection can be modelled with existing building physics simulation tools, such as COMSOL. Finally, the internal macro-scale convection increases the effective U-value by up to 90 % for the highest temperature difference in steady-state conditions. This effect appears to diminish under dynamic boundary conditions, with a calculated effective U-value being within the uncertainty of the steady-state case with the lowest temperature difference, indicating that it might be less influential under real conditions.</p
Painless construction of unconditional bases for anisotropic modulation and Triebel-Lizorkin type spaces
No full textWe construct smooth localized orthonormal bases compatible with anisotropic Triebel-Lizorkin and Besov type spaces on Rd. The construction is based on tensor products of so-called univariate brushlet functions that are based on local trigonometric bases in the frequency domain, and the construction is painless in the sense that all parameters for the construction are explicitly specified. It is shown that the associated decomposition system form unconditional bases for the full family of Triebel-Lizorkin and Besov type spaces, including for the so-called α-modulation and α-Triebel-Lizorkin spaces. In the second part of the paper we study nonlinear m-term approximation with the constructed bases, where direct Jackson and Bernstein inequalities for m-term approximation with the tensor brushlet system in α-modulation and α-Triebel-Lizorkin spaces are derived. The inverse Bernstein estimates rely heavily on the fact that the constructed system is non-redundant.</p
A novel wave energy converter with an extended operational range for a wide range of wave conditions
No full textWave energy converters (WECs) generally operate within a specific range of wave conditions. In circumstances where wave conditions exceed established limits, the operation of WECs must be suspended for safety reasons, resulting in a waste of wave energy resources. To enhance the power generation capacity, a novel WEC with an extended operational range for a wide range of wave conditions has been developed. The device captures wave energy using a controllable-valve buoy (CVB) and is integrated with a direct-drive power take-off (PTO) system based on a magnetic lead screw (MLS) for energy conversion. By adjusting the controllable valve to alter the closed-volume mass of the buoy, wave thrust can be mitigated, enabling safe operation even beyond the rated range and thereby extending effective power generation time. Consequently, a 1:13.3 scale experimental prototype was produced and tested in a physical wave tank. The experimental results indicate that the CVB has the capacity to extend the operational wave range of the WEC. Moreover, the analysis reveals a negative correlation between wave thrust, PTO force, and capture width ratio (CWR) with valve radius of the controllable valve.</p
Adaptive Fuzzy Logic-Based Coordinated Tuning of Distributed Virtual Synchronous Generators Parameters for Frequency Oscillation Suppression in Islanded Microgrids
No full textIn islanded microgrids with multiple Virtual Synchronous Generators, challenges such as frequency oscillations, power fluctuations, and dynamic instability become particularly pronounced during transient conditions. This paper proposes a novel and adaptive fuzzy logic-based control method for the simultaneous tuning of inertia and damping coefficients in multi-VSG systems operating in islanded mode. The innovation of the proposed method lies in the concurrent utilization of local frequency and the Center of Inertia frequency to enable intelligent decision-making for dynamic control. By analyzing the instantaneous frequency deviation and its rate of change, the optimal values of the control coefficients are adaptively determined to effectively suppress frequency oscillations. Comprehensive simulations demonstrate that the proposed approach, which coordinates adaptive inertia and damping parameters simultaneously through a fuzzy logic framework, achieves faster damping of frequency oscillations and enhanced dynamic stability compared with recent feedforward, feedback, and reactive-power-based damping methods reported in the literature.<br/
Managing an ageing workforce:workplace retention practices and early labour market exit
No full textThis study addresses a critical gap in our understanding of how the employer and workplace context influences the working career of older employees. Leveraging linked employer-employee data, this study examines the impact of workplace retention practices on an early labour market exit for employees aged fifty-five to sixty-four in Denmark. The findings reveal that, for those eligible for early retirement, work environment adaptation, re-employment of retired employees, and positive views of older employees' productivity significantly contribute to avoiding early retirement. However, these workplace retention practices do not influence unemployment, emphasizing their effectiveness in postponing early retirement rather than mitigating job loss. Moreover, the analysis shows that employees with managerial roles and high skill levels benefit more from workplace retention practices in terms of avoiding both early retirement and unemployment. This finding highlights the employer's key role in shaping inequalities in an ageing workforce by selectively providing opportunities to extend working lives.</p
Predictive risk modelling in child and family welfare:reflections on a Danish case
No full textBased on a Danish research project in child and family welfare services, we present reflections, exchanges and dialogue from workshops held at one national and four international conferences (please see details in the ‘Acknowledgements’). The article highlights shared discussions and perspectives on challenges across European countries by examining predictive risk modelling (PRM) technologies in evolving organisational contexts. We provide insights into implications for practice, research and policy based on how social work researchers envision the future of PRM.Based on a Danish research project in child and family welfare services, we present reflections, exchanges and dialogue from workshops held at one national and four international conferences (please see details in the ‘Acknowledgements’). The article highlights shared discussions and perspectives on challenges across European countries by examining predictive risk modelling (PRM) technologies in evolving organisational contexts. We provide insights into implications for practice, research and policy based on how social work researchers envision the future of PRM
Integrated reporting quality and negative ESG media coverage:Empirical evidence from South Africa
No full textThis study draws upon media agenda-setting theory to investigate the relationship between negative media coverage around environmental, social, and governance (ESG) issues and the quality of integrated reporting (IR). In particular, we examine the top 100 South African listed companies in the 2013–2018 timeframe for 317 firm-year observations. Our results reveal that IR quality is positively related to negative ESG media coverage. Thus, a company exposed to more media pressure issues higher-quality IR consistent with its need to face scrutiny and potential reputational damage and to restore or maintain its legitimacy. Results are robust to different measures of negative ESG media coverage, controlling for ESG disclosures, and are confirmed by analyses aimed at addressing endogeneity (instrumental variable approach, firm-fixed effects, and matched samples). Subsample analyses show that financial sector reputational concerns do not impact our results. Additional tests show no long-term effects of negative media coverage on IR quality and that sustainability embeddedness alleviates a company’s response to negative ESG news in terms of enhanced reporting