1,721,158 research outputs found
A Multi-Domain Approach to Explanatory and Predictive Thermal Comfort Modelling in Offices
Full text linkIt is well known that physical variables, such as temperature, exert a significant influence on occupants' thermal comfort in office buildings. Despite this knowledge, models that are currently used to predict thermal comfort fail to do so accurately, resulting in a mismatch between design conditions and actual thermal comfort conditions. The assumption is that exclusive attention to physical variables is insufficient for understanding or predicting thermal comfort. Contextual, social and personal variables may also affect thermal comfort in office buildings and interact with each other. The question arises as to how a multi-domain approach can aid in explaining and predicting thermal comfort in offices. In this study, a unique dataset containing indoor environment, demographic, occupancy and personality related variables is used to construct two types of thermal comfort models. The dataset contains 524 observations, collected during summertime in two office buildings in the Netherlands. Firstly, structural equation modelling (SEM) is used to construct an explanatory model, with the aim to identify significant variables affecting thermal comfort, as well as the interactions between them. Secondly, machine learning is used to train four binary classification models to predict thermal discomfort. For the investigated cases, SEM suggests that thermal discomfort is significantly affected by (i) temperature, (ii) sound pressure level, (iii) the interaction between temperature, sound pressure level and illuminance, and (iv) the interaction between gregariousness and occupancy count. The four predictive models are subsequently trained using only the significant variables. Nevertheless, the weighted F1-score for all four models ranges between 0.55 and 0.59, indicating weak predictive performance. The results show that significant influencers are not necessarily good predictors of thermal discomfort. Future researchers are encouraged to combine explanatory and predictive modelling techniques, in order to test whether variables that are relevant to the domain are useful for prediction
Response of low-cost environmental monitors to typical emission events in daycare centers
Full text linkDaycare centers (DCCs), the first program for the social development of young children (0-5 years old), are the most important place for young children besides their homes. Continuous indoor air quality (IAQ) monitoring in DCCs is a means to assess the IAQ and assure a healthy and comfortable environment for infants and toddlers. To date, an extensive array of low-cost air quality monitors (LCMs) is available on the commercial market. Still, only a limited number of these LCMs have been subjected to any research-based evaluation. Furthermore, performance evaluations of low-cost sensors in previous literature are mainly focused on residential emission activities. To the best of our knowledge, there is no research into simulating emission sources related to DCCs scenarios yet. Therefore, this study is aimed to evaluate the response of one type of LCM (2 units) to typical emissions events related to DCCs in detecting the IAQ parameters, that is, particulate matter (PM2.5, PM10), carbon dioxide (CO2), total volatile organic compounds (TVOC), temperature (T), and relative humidity (RH). The LCMs were compared to outcomes from research-grade instruments (RGIs). All the experiments were performed in a climate chamber, where 3 kinds of typical activities (Background test; Arts-and-crafts events; Cleaning events; in a total of 20 events) were simulated by recruited subjects in an indoor climate condition (cool and dry [20±1 ℃ & 40±5% ℃]). The IAQ parameters sensed by the LCM detected the majority of events, despite a difference in the magnitude of responses. Intra-sensor consistency was significantly strong for all IAQ parameters, with a mean coefficient of variation of 4.14%. The LCM particle sensor underestimated the reference concentrations, with a mean RMSE of 12.8 μg/m³ for PM2.5 and 36.5 μg/m³ for PM10. Although TVOC and CO2 sensors reported a weak quantitative response, both had a close correlation with RGIs’ data, with R2 values in the range of 0.8-1.0 and 0.5-1.0, respectively. A good qualitative and quantitative agreement was observed in both T (within 1.1°C) and RH sensor (within 1%). In summary, this study reveals that the LCMs investigated are useful in providing IAQ-based monitoring in the specific application scenarios of daycare centers
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Practical experiences from the implementation of extensive sensoring in a modern building
Full text linkThe extensive use of sensors is quickly becoming a standard feature of modern new buildings. Apart from the use of regular Building Management System (BMS) data, we see the addition of sensors that monitor in more detail the indoor environmental quality and the use and performance of innovative (and local) system solutions. This is also combined with integrated energy solutions at supra-building level. The assumption is that all these data are valuable to arrive at buildings that can optimize their operation towards indoor environmental and other sustainable performance indicators. In this research, data from a large modern building that combines office and educational rooms, features an innovative façade design and is connected to an aquifer thermal energy storage are considered. In order to perform detailed analyses, several sensor and data related issues had to be resolved first. In this paper we provide a procedure for structuring the data as was available for this specific building, originating from different sources. The outcomes provide a practical basis for other buildings to assess the correctness and quality of the sensor data and the analysis potential. An example of an analysis is presented. In addition, the paper demonstrates how the obtained measurement data can be used to calibrate a simulation model that is employed to analyse the ventilative cooling potential of the innovative façade in comparison to shading
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Measurements of Capture Efficiency of Range Hoods in Homes
No full textA major source of pollutants in homes is cooking and as homes get tighter in the pursuit of lower energy use (particularly near zero energy), the concentration of cooking pollutants increases. The best way to remove cooking pollutants is to use a range hood above the cooking surface. Ideally, we want a range hood to use little energy and have high capture efficiency to minimize the required air flow to capture the cooking pollutants. Currently there are no standards for rating range hoods for capture efficiency In this study, measurements of range hood capture efficiency were made a tight kitchen-room built in a laboratory chamber, and a methodology for standardizing measurement of capture efficiency was developed. The results for a wall mounted range hood, showed that up to half of the cooking pollutants were not captured at a flow rate of 230 m3/h. A more detailed set of measurements mapped the pollution distribution in the room, and showed that the pollutants escape more at the sides of the cooktop. These preliminary results suggest that more measurements should be conducted investigating the capture efficiency at different pollutant source temperature, size and location, and for different range hood type and mounting height
Control and prevention of ice formation and accretion on heat exchangers for ventilation systems
Full text linkIn cold climates, the application of mechanical ventilation systems with heat recovery like are airto-air exchangers is used for reducing energy consumption for heating buildings by transferring heat exhausted air to supply air. However, increase efficiency of heat exchanger results in lower exhaust air temperatures and Ice formation on heat exchanger fins, which can cause problem and is not favourable. Therefore, prevention and control of ice formation on heat exchangers is necessary. The existing methods are divided into two different methods: active and passive ice control methods. The active methods are e.g. bypass, recirculation, preheating. The passive methods relate to the surface characteristics of the heat exchanger fins as they have effect on ice formation in initial phase. All these methods have varying levels of success, cost, and effectiveness, which are depending on the heat exchangers operating condition and construction. Since, the active method are reducing efficiency of heat exchanger and the passive methods are not permanent solution it can be suggested that the optimum ice protection method may be a combination of both methods. The aim of this paper is to review and evaluate the current methods to provide new insight of concern for the ice formation problem
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