19 research outputs found
Correction to:Minimizing a Wireless Passive LC-Tank Sensor to Monitor Bladder Pressure: A Simulation Study (Journal of Medical and Biological Engineering, (2017), 37, 6, (800-809), 10.1007/s40846-017-0244-2)
No full textThe article “Minimizing a Wireless Passive LC-Tank Sensor to Monitor Bladder Pressure: A Simulation Study”, written by Jacob Melgaard, Johannes J. Struijk, Nico J. M. Rijkhoff was originally published Online First without open access. After publication in volume [37], issue [6], page [800–809] the author decided to opt for Open Choice and to make the article an open access publication. Therefore, the copyright of the article has been changed to</p
Correction: Melgaard et al. Fault Detection and Diagnosis Encyclopedia for Building Systems: A Systematic Review. Energies 2022, 15, 4366
No full textError in Table [...
Underfloor Heating Operation in NZEB Buildings – To Better Understand Occupant’s Comfort and Reasons Behind Energy Performance Gap
No full textRadiant heating is a well-established solution that is widely adopted in existing and new nearly zero energy buildings (NZEBs). Underfloor heating (UFH) is known for its many advantages, e.g., allowing access to low-grade heat sources such as heat pumps and low temperature district heating (LTDH) systems, and secure comfortable indoor environment. This study presents a long-term monitoring campaign of an NZEB building fully covered with a UFH system. Monitoring covers approximately one entire heating season, with the experiment aiming to decrease the operational indoor temperature and energy use for space heating while investigating the occupants’ acceptance to this new thermal comfort situation and registering their feedback about perceived thermal comfort. The experiment results show that there is a significant reduction in the operation of the hydraulic system and water circulation in the UFH that is negatively perceived by the occupants who are used to feeling the warm floor. The paper highlights that the UFH, in combination with occupant’s comfort preferences, can be the reason for NZEBs to operate with elevated indoor temperatures and to use more energy than anticipated. Results indicate that UFH in bathrooms is operated all year long due to occupants striving to feel the warm floor. The findings can significantly contribute to the advancement of innovative control strategies for achieving thermal comfort in NZEB buildings with radiant water-based heating systems and consideration for other placement of radiant emitters in the spaces.</p
Decentralization and public services : the case of immunization
No full textThe author studies the impact of political decentralization on childhood immunization, an essential public service provided in almost all countries. He examines the relationship empirically using a time-series data set of 140 low- and middle-income countries from 1980 to 1997. The author finds that decentralization has different effects in low- and middle-income countries. In the low-income group, decentralized countries have higher coverage rates than centralized ones, with an average difference of 8.5 percent for measles and DTP3 vaccines. In the middle-income group, the reverse effect is observed: decentralized countries have lower coverage rates than centralized ones, with an average difference of 5.2 percent for the same vaccines. Both results are significant at the 99 percent level. Modifiers of the decentralization-immunization relationship also differ in the two groups. In the low-income group, development assistance reduces the gains from decentralization. In the middle-income group, democratic government mitigates the negative effects of decentralization, and decentralization reverses the negative effects of ethnic tension and ethno-linguistic fractionalization, but institutional quality and literacy rates have no interactive effect either way. Similar results are obtained whether decentralization is measured with a dichotomous categorical variable or with more specific measures of fiscal decentralization. The study confirms predictions in the theoretical literature about the negative impact of local political control on services that have public goods characteristics and inter-jurisdictional externalities. The author discusses reasons for the difference between low- and middle-income countries.Public Health Promotion,Banks&Banking Reform,Health Monitoring&Evaluation,Decentralization,Municipal Financial Management,National Governance,Banks&Banking Reform,Municipal Financial Management,Health Monitoring&Evaluation,Governance Indicators
A novel Monte Carlo modelling method to support control strategies development in building ventilation
No full textVentilation is critical for maintaining thermal comfort and air quality in buildings. However, developing ventilation control is challenging due to the large number of control variables and performance criteria. Typical ventilation controls are On-Off controls, time schedules, and PI/PID controls. Specific parameters are tuned based on simple rules of thumb and the engineer’s experience. Although building simulation tools are commonly applied, they are normally used to evaluate the performance of certain control strategies rather than guide the development of these control strategies. This study presents a novel Monte Carlo modelling method that supports the early-stage development of ventilation control. The method consists of the following steps: (1) Creating an initial building model, (2) Identifying relevant control variables and assigning probability distributions, (3) Executing Monte Carlo simulations, (4a) Applying filters to assess the outcomes, (4b) Performing sensitivity analysis on control variables, (5) Selecting a ventilation control strategy fulfilling control objectives. The method is tested on a classroom equipped with a hybrid ventilation system. The case study demonstrates that the novel approach, allows ventilation designers to systematically identify high-performance control solutions for multiple control variables and performance requirements. Thus, offering clear advantages over the traditional trial-and-error method
Double-skin façade simulation with computational fluid dynamics:A review of simulation trends, validation methods and research gaps
No full textDynamic simulation of a double-skin façade (DSF) with computational fluid dynamics (CFD) can be challenging due to the lack of validated models and benchmarking datasets. Furthermore, there is a lack of consensus in the scientific community on what constitutes a successfully validated DSF model. The present review study identifies simulation trends and research gaps for DSFs simulated with CFD. Additionally, this article presents a series of CFD simulations in which key aspects of the DSF modelling are varied: 2D or 3D modelling approaches, turbulence viscosity models (TVMs), radiation models, and wall function. These simulation results are compared to the empirical data (both temperature and velocity fields) of a benchmark test with laboratory-controlled boundary conditions. This analysis shows that using the k-ε RNG model with enhanced wall treatment and surface-to-surface (S2S) radiation model yields the best results for the 2D case of natural convection flow. Moreover, it is shown that accounting for the velocity field in the validation process is essential to ensure the suitability of a model. Finally, the authors advocate for the use of selected dimensionless numbers to improve the comparability of the different DSF scientific studies. This would also help to identify relevant experimental datasets for validation and suitable CFD simulation settings for specific DSF cases.</p
Fault Detection and Diagnosis Encyclopedia for Building Systems:A Systematic Review
No full textThis review aims to provide an up-to-date, comprehensive, and systematic summary of fault detection and diagnosis (FDD) in building systems. The latter was performed through a defined systematic methodology with the final selection of 221 studies. This review provides insights into four topics: (1) glossary framework of the FDD processes; (2) a classification scheme using energy system terminologies as the starting point; (3) the data, code, and performance evaluation metrics used in the reviewed literature; and (4) future research outlooks. FDD is a known and well-developed field in the aerospace, energy, and automotive sector. Nevertheless, this study found that FDD for building systems is still at an early stage worldwide. This was evident through the ongoing development of algorithms for detecting and diagnosing faults in building systems and the inconsistent use of the terminologies and definitions. In addition, there was an apparent lack of data statements in the reviewed articles, which compromised the reproducibility, and thus the practical development in this field. Furthermore, as data drove the research activity, the found dataset repositories and open code are also presented in this review. Finally, all data and documentation presented in this review are open and available in a GitHub repository.</p
Assessment of thermal comfort at the building level: Evaluation of aggregation methods with a Danish case study of a campus building
No full textSix methods for aggregating local thermal comfort scores in six offices to a single global score are investigated. using data collected by the building management system in a campus building of Aalborg University. Three static: 1) number of rooms weighted mean, 2) area-weighted mean, 3) desk-weighted mean, and three dynamic: 4) simple occupancy-weighted mean (PIR sensors), 5) advanced occupancy-weighted mean (PIR sensors mixed with the number of desks), 6) number of the occupants-weighted mean (camera readings). A notable disparity emerged between static methods, which rely solely on fixed parameters, and dynamic methods, which account for time-dependent factors over short timeframes. Dynamic methods consistently yielded lower global scores, irrespective of individual room performance. The difference can be up to 15% monthly. The PIR sensors, which are now commonly used in office or education buildings to control artificial lighting are a good indication of the occupancy (only present and not present). The information on number of occupants in the offices, collected by installed cameras, did not provide significantly better results in the analysed case study
Energy efficiency enhancement in two European data centers through CFD modeling
No full textThe new reporting scheme adopted by the European Union focuses on the efficiency assessment of data centers based on key performance indicators (KPIs). This has the potential to lead to further measures for improving energy efficiency of data centers. Consequently, a systematic approach is crucial for assessing and improving data center performance. This study investigates efficiency assessment of two European pilot data centers, located in Denmark and Poland, according to the KPIs calculated through Computational Fluid Dynamics (CFD) simulations of airflow and thermal structures. Two separate experimental approaches were adopted at the pilot sites. One measured airflow and temperatures using external sensors at server inlets and outlets, while the other measured inlet temperatures from embedded server sensors. The good agreement observed between simulated and experimental data confirmed the accuracy of the computational model. The validated CFD model was applied to investigate efficiency improvement opportunities by retrofitting the thermal environment such as rack positioning, containment implementation, and guided airflow control. A series of numerical simulations are performed using the validated numerical model and KPIs are calculated for each design. Numerical simulations demonstrate that the efficiency of an existing data center can be enhanced by up to 75% using the presented approach, although the improvement varied significantly with the specific KPIs. The computational approach proposed here can be readily generalized to guide the efficiency assessment and improvement of existing data centers.</p
Determinants of structural and functional plasticity of a widely conserved protease chaperone complex
No full textChanneling of misfolded proteins into repair, assembly or degradation pathways is often mediated by complex and multifunctional cellular factors. Despite detailed structural information, the underlying regulatory mechanisms governing these factors are not well understood. The extracytoplasmic heat-shock factor DegP (HtrA) is a well-suited model for addressing mechanistic issues, as it is regulated by the common mechanisms of allostery and activation by oligomerization. Site-directed mutagenesis combined with refolding and oligomerization studies of chemically denatured DegP revealed how substrates trigger the conversion of the resting conformation into the active conformation. Binding of specific peptides to PDZ domain-1 causes a local rearrangement that is allosterically transmitted to the substrate-binding pocket of the protease domain. This activated state readily assembles into larger oligomeric particles, thus stabilizing the catalytically active form and providing a degradation cavity for protein substrates. The implications of these data for the mechanism of protein quality control are discussed.Channeling of misfolded proteins into repair, assembly or degradation pathways is often mediated by complex and multifunctional cellular factors. Despite detailed structural information, the underlying regulatory mechanisms governing these factors are not well understood. The extracytoplasmic heat-shock factor DegP (HtrA) is a well-suited model for addressing mechanistic issues, as it is regulated by the common mechanisms of allostery and activation by oligomerization. Site-directed mutagenesis combined with refolding and oligomerization studies of chemically denatured DegP revealed how substrates trigger the conversion of the resting conformation into the active conformation. Binding of specific peptides to PDZ domain-1 causes a local rearrangement that is allosterically transmitted to the substrate-binding pocket of the protease domain. This activated state readily assembles into larger oligomeric particles, thus stabilizing the catalytically active form and providing a degradation cavity for protein substrates. The implications of these data for the mechanism of protein quality control are discussed
