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Biological contamination of fresh produce by fungi in storage is becoming a serious problem. Gaseous chlorine dioxide (ClO2) has been used to prevent fungal growth on fresh produce; however, the specific effects of gaseous ClO2 at concentrations low enough to be safe for the human body on fungal growth remain unknown. Therefore, in this study, we aimed to investigate the effect of low-concentration gaseous ClO2 on fungal growth in sweet potatoes over 1 month. Here, a mechanochemical reaction involving the collision of two types of powders was used to produce low concentrations of gaseous ClO2. The experiment was conducted in a container and chlorine dioxide gas was diffused by a circulator to verify its microbiostatic effect in a large space. A clear microbiostatic effect was observed in potatoes without skin when exposed to low-concentration ClO2 for 3 days. Notably, low concentrations (< 1.0 ppm) of ClO2 reduced Rhizopus stolonifer growth in sweet potatoes with skin over 1 month. Therefore, low concentrations of gaseous ClO2 are sufficient to inhibit fungal growth via gas diffusion. [ABSTRACT FROM AUTHOR]

Stringent fire prevention requirements are imperative in expansive environments. Fire detection in diverse large-scale settings typically relies on sensor-based or AI-driven target detection methods. Traditional fire detectors often suffer from false alarms and missed detections, failing to meet the fire safety requirements of large-scale structures. Many existing target detection algorithms are characterized by substantial model sizes. Some detection terminals in large structures face challenges deploying these models due to constrained computational resources. To address this issue, we propose a lightweight model, YOLOv8-EMSC, derived from YOLOv8n. The incorporation of C2f_EMSC, replacing the C2f module, significantly reduces the model parameters in the enhanced YOLOv8-EMSC model compared to YOLOv8n, thereby enhancing model inference speed. Extensive testing and validation using a custom-built large-scale infrared fire dataset demonstrates a 9.6 % reduction in parameters compared to the baseline model for YOLOv8-EMSC, achieving an average precision of 95.6 %, surpassing both the baseline and mainstream models and significantly enhancing fire detection accuracy in expansive environments. [ABSTRACT FROM AUTHOR]

Abstract Biological contamination of fresh produce by fungi in storage is becoming a serious problem. Gaseous chlorine dioxide (ClO2) has been used to prevent fungal growth on fresh produce; however, the specific effects of gaseous ClO2 at concentrations low enough to be safe for the human body on fungal growth remain unknown. Therefore, in this study, we aimed to investigate the effect of low-concentration gaseous ClO2 on fungal growth in sweet potatoes over 1 month. Here, a mechanochemical reaction involving the collision of two types of powders was used to produce low concentrations of gaseous ClO2. The experiment was conducted in a container and chlorine dioxide gas was diffused by a circulator to verify its microbiostatic effect in a large space. A clear microbiostatic effect was observed in potatoes without skin when exposed to low-concentration ClO2 for 3 days. Notably, low concentrations (

Buildings with large open spaces in which chemicals are handled are often exposed to the risk of explosions. Computational fluid dynamics is a useful and convenient way to investigate contaminant dispersion in such large spaces. The turbulent Schmidt number (Sct) concept has typically been used in this regard, and most studies have adopted a default value. We studied the concentration distribution for sulfur hexafluoride (SF6) assuming different emission rates and considering the effect of Sct. Then we examined the same problem for a light gas by assuming hydrogen gas (H2) as the contaminant. When SF6 was considered as the contaminant gas, a variation in the emission rate completely changed the concentration distribution. When the emission rate was low, the gravitational effect did not take place. For both low and high emission rates, an increase in Sct accelerated the transport rate of SF6. In contrast, for H2 as the contaminant gas, a larger Sct could induce a decrease in the H2 transport rate. [ABSTRACT FROM AUTHOR]

The energy consumption of air conditioning systems in large spaces is a concern due to inefficiencies caused by the high ceiling. This paper presents the Green aIr-distribution System (GIS) retrofitting technique as a solution to reduce energy consumption and optimize thermal comfort in a large Hong Kong sports center to achieve carbon neutrality. A comparison is made between the existing air distribution system with ceiling supply and return as baseline model and the GIS with occupied wall supply and ceiling return as retrofit models regarding ventilation performance, thermal comfort, and energy aspects. Computational fluid dynamics (CFD) is employed to analyze the average operative temperature, airspeed, and other thermal comfort parameters. The findings demonstrate that implementing the GIS in the large sports center allows for a 1.5 °C increase in the supply temperature without significantly compromising thermal comfort. The algorithm for developing GIS for the large space application is also discussed. Additionally, the GIS model exhibits notable improvements in ventilation factors, such as Local Mean Age (LMA), Local air change index (LACI), and Air Distribution Performance Index (ADPI), resulting in improved air quality and reduced energy use within the occupied space.

The energy consumption of air conditioning systems in large spaces is a concern due to inefficiencies caused by the high ceiling. This paper presents the Green aIr-distribution System (GIS) retrofitting technique as a solution to reduce energy consumption and optimize thermal comfort in a large Hong Kong sports center to achieve carbon neutrality. A comparison is made between the existing air distribution system with ceiling supply and return as baseline model and the GIS with occupied wall supply and ceiling return as retrofit models regarding ventilation performance, thermal comfort, and energy aspects. Computational fluid dynamics (CFD) is employed to analyze the average operative temperature, airspeed, and other thermal comfort parameters. The findings demonstrate that implementing the GIS in the large sports center allows for a 1.5 °C increase in the supply temperature without significantly compromising thermal comfort. The algorithm for developing GIS for the large space application is also discussed. Additionally, the GIS model exhibits notable improvements in ventilation factors, such as Local Mean Age (LMA), Local air change index (LACI), and Air Distribution Performance Index (ADPI), resulting in improved air quality and reduced energy use within the occupied space. [ABSTRACT FROM AUTHOR]

Due to the large height and span of indoor spaces, efficient indoor ventilation performance may be difficult to achieve using the side air supply for large halls, to control the indoor air pollutants or reduce the infection risk, such as the transmission of COVID-19 within the breathing zone of occupants. An efficient Ventilation Mode with Deflector and Slot air outlets (VMDS) was developed by this study. The use of a deflector with slot air outlets was introduced by utilizing jet collision and adhesion effect to accentuate the ventilation performance of the side air supply for the large space. The numerical simulation model used in this study was validated experimentally. The VMDS was compared with three other side air supply modes used in large spaces, and the results were evaluated comprehensively. The results show that VMDS is effective in reducing indoor air pollutant concentrations and transmission of infectious diseases in large spaces while satisfying the energy efficiency and thermal comfort requirements. Compared with the common side-supply and side-return ventilation modes, VMDS can reduce indoor air pollutant concentration by nearly 40%, reduce the transmission risk of infectious disease to less than 1% at a low air change rate and increase the ventilation efficiency from about 0.85 to about 1.2. In addition, VMDS can theoretically reduce ventilation energy consumption by about 85%. [ABSTRACT FROM AUTHOR]

With the development of the NB-IoT (Narrow band Internet of Things) and smart cities, coupled with the emergence of smart smoke sensors, new requirements and issues have been introduced to study on the deployment of sensors in large spaces. Previous research mainly focuses on the optimization of wireless sensors in some monitoring environments, including three-dimensional terrain or underwater space. There are relatively few studies on the optimization deployment problem of smart smoke sensors, and leaving large spaces with obstacles such as libraries out of consideration. This paper mainly studies the deployment issue of smart smoke sensors in large spaces by considering the fire probability of fire areas and the obstacles in a monitoring area. To cope with the problems of coverage blind areas and coverage redundancy when sensors are deployed randomly in large spaces, we proposed an optimized deployment strategy of smart smoke sensors based on the PSO (Particle Swarm Optimization) algorithm. The deployment problem is transformed into a multi-objective optimization problem with many constraints of fire probability and barriers, while minimizing the deployment cost and maximizing the coverage accuracy. In this regard, we describe the structure model in large space and a coverage model firstly, then a mathematical model containing two objective functions is established. Finally, a deployment strategy based on PSO algorithm is designed, and the performance of the deployment strategy is verified by a number of simulation experiments. The obtained experimental and numerical results demonstrates that our proposed strategy can obtain better performance than uniform deployment strategies in terms of all the objectives concerned, further demonstrates the effectiveness of our strategy. Additionally, the strategy we proposed also provides theoretical guidance and a practical basis for fire emergency management and other departments to better deploy smart smoke sensors in a large space. [ABSTRACT FROM AUTHOR]

The ring-ribbed tank is the key equipment of cooling system of deep-sea manned submersible. The heat transfer characteristics of the outer wall and the heat transfer and flow characteristics of the inner flow channel of the ring-ribbed tank for different inlet and outlet temperatures and flow rates were studied through a water tank test. The results indicate that Nusselt number for the inner flow channel correlates with Reynolds and Prandtl numbers, while for the outer wall, it correlates with Grashof and Prandtl numbers with an overall error within 5%. A numerical study using the Realizable k-ε turbulence model and Boussinesq approximation of the flow-solid conjugate heat transfer is conducted, which can accurately determine the heat exchange capacity and the import and export differential pressure with an average relative error of 1.98% for hot water temperature and 7.73% for shell wall temperature. Additional simulations for determining the heat transfer capacity and flow resistance characteristics of the ring-ribbed tank in open water results demonstrate that the differential pressure and its coefficient are basically consistent with model test results. The cooling system can achieve a heat transfer rate of up to 17 kW with an external seawater flow velocity of approximately 2 knots. [Display omitted] • Heat transfer in ring-ribbed tank for deep-sea submersibles was analyzed experimentally. • Numerical simulation validates heat exchange capacity with 1.98% avg. Error. • Realizable k-ε turbulence model enhances prediction accuracy in cooling systems. • Optimized design achieves up to 17 kW heat transfer at 2 knots seawater flow velocity. [ABSTRACT FROM AUTHOR]

Occupancy dynamics can significantly influence indoor thermal environments, especially in large indoor spaces. It is difficult for conventional feedback control systems to respond promptly to occupancy dynamics because of the substantial thermal inertia of large spaces, which leads to unfavorable thermal conditions in environments regulated by such systems. To address this challenge, this study proposes an air supply control approach based on artificial neural networks (ANNs). In the proposed approach, a large space is divided into multiple zones and an ANN model is used to characterize the relationship between occupancy dynamics and the supply air flow rates of each zone, thereby expediting the response of the air-conditioning system to occupancy dynamics. First, a multi-zone thermal environment model was developed to accurately emulate the thermal behavior of each zone. Next, employing the developed model of the environment, the optimal air flow rates required for each zone to maintain the desired thermal environment were estimated for various boundary conditions, which were used as pretraining data for four candidate ANNs. Finally, the best-performing ANN candidate, Long Short-Term Memory (LSTM), was adopted in a case study building via a comparison against several conventional air supply control methods. The results from the case studies demonstrate that the proposed approach can effectively expedite the system response to occupancy dynamics, thereby minimizing the occurrence of overcooling and overheating, and lowering the occupancy-weighted thermal discomfort level by 73.1 %. The proposed approach holds promise for real-time applications based on digital twin architecture. [Display omitted] • A thermal environment model is developed to emulate thermal behaviors of large spaces. • The impacts of occupancy dynamics on temperature control are investigated. • An ANN-based air supply method is proposed to deal with occupancy dynamics. • This approach can lower the occupancy-weighted thermal discomfort level by 73.1 %. • Data-driven HVAC control holds application promise under digital twin architecture. [ABSTRACT FROM AUTHOR]

In this article the analysis of process, tendencies of change of unipolar model of a world order on multipolar is carried out. The most essential characteristics of liberalism as the most characteristic expression of the unipolar model of the world order are given. In the course of the study, special attention is paid to the analysis of the most significant events that mark the process of changing the model of the world order. The “Order of Large Spaces” as a supposed concept of legitimacy of the new world order is presented as a proposed structure of the world order. The author pays special attention to the potential of Russia to consolidate the Large Eurasian space and to the existential necessity of this process. The result of this study can be considered the justification of the Eurasian project as an expression of the essence of a Large space, the process of integration of the post-Soviet space, the key civilizational and foreign policy of Russia.

Augmented reality (AR) is widely used to guide users when performing complex tasks, for example, in education or industry. Sometimes, these tasks are a succession of subtasks, possibly distant from each other. This can happen, for instance, in inspection operations, where AR devices can give instructions about subtasks to perform in several rooms. In this case, AR guidance is both needed to indicate where to head to perform the subtasks and to instruct the user about how to perform these subtasks. In this paper, we propose an approach based on user activity detection. An AR device displays the guidance for wayfinding when current user activity suggests it is needed. We designed the first prototype on a head-mounted display using a neural network for user activity detection and compared it with two other guidance temporality strategies, in terms of efficiency and user preferences. Our results show that the most efficient guidance temporality depends on user familiarity with the AR display. While our proposed guidance has not proven to be more efficient than the other two, our experiment hints toward several improvements of our prototype, which is a first step in the direction of efficient guidance for both wayfinding and complex task completion. [ABSTRACT FROM AUTHOR]

Large space buildings play a significant role in modern society because of their environmental advantages and market value. While the zonal model is promising for the efficient and rapid evaluation of the stratified thermal environment, there is a lack of a reasonable and convenient zoning strategy with the advent of modern computing. This paper presents a universal and practical zonal model, in which a simplified momentum equation is applied to consider air momentum preservation, transformation, and dissipation. Hence, the zoning structure is generalized and flexible. Moreover, limiting the dimensionless temperature constraint between adjacent zones establishes the connection between thermal nonuniformity and zoning results automatically. Simultaneously, the dimension and number of zones should be restricted within reasonable ranges to satisfy the characteristics of zonal simulation and reach the criteria of convergence. To further explore and validate the zonal model, a reduced-scale experimental model was constructed to replicate the thermal stratification in a mechanically ventilated large space by considering many crucial realistic factors. A particle image velocimetry (PIV) measurement was then conducted to visualize the airflow pattern and support the partition of zones. The results showed that the zonal simulation with adaptive zoning method can realize a similar accuracy with fewer zones and exhibit a better tolerance for zoning results compared to the conventional empirical zoning method. Furthermore, a case study of an atrium was performed to demonstrate the practicality and efficiency of the method for long-term dynamic simulations of complex thermal environments and building energy use. [ABSTRACT FROM AUTHOR]

A microstrip antenna array with large space and narrow beamwidth working at 24 GHz is presented in this paper. In some millimeter‐wave radar systems, it is often necessary for transmitting antenna with high gain and narrow beamwidth to avoid interference from other information. According to the theory of antenna array, when the number and spacing of the subarrays and the sidelobe level are given, the half‐power beamwidth can be basically determined. In previous studies, the subarray spacing of the transmitting antenna is usually taken as a dielectric wavelength λg. In this paper, under the condition that the number of subarrays is given and no grating lobe is generated, the half power beamwidth is further narrowed by increasing the subarray spacing. The final subarray space of the 12 × 8 antenna array is 11.5 mm, that is, 1.68 dielectric wavelength (λg), and the half power beamwidth of H‐plane is only 5.5°. The simulated and measured results are presented and discussed. Through processing and testing, it is proved that the antenna array has good performance and can be applied to 24 GHz automotive collision avoidance radar or 24 GHz perimeter security radar. [ABSTRACT FROM AUTHOR]

Augmented reality (AR) is widely used to guide users when performing complex tasks, for example, in education or industry. Sometimes, these tasks are a succession of subtasks, possibly distant from each other. This can happen, for instance, in inspection operations, where AR devices can give instructions about subtasks to perform in several rooms. In this case, AR guidance is both needed to indicate where to head to perform the subtasks and to instruct the user about how to perform these subtasks. In this paper, we propose an approach based on user activity detection. An AR device displays the guidance for wayfinding when current user activity suggests it is needed. We designed the first prototype on a head-mounted display using a neural network for user activity detection and compared it with two other guidance temporality strategies, in terms of efficiency and user preferences. Our results show that the most efficient guidance temporality depends on user familiarity with the AR display. While our proposed guidance has not proven to be more efficient than the other two, our experiment hints toward several improvements of our prototype, which is a first step in the direction of efficient guidance for both wayfinding and complex task completion.

Summary: Large confined space has high incidence of fires, which seriously threatens the safety of people working there. Understanding the distribution of smoke in such large space is critical to fire development prediction and smoke control. Three improved methods for the stratification interface prediction of fire smoke are developed, including of improved intra‐variance, integral ratio and N‐percentage methods. In these methods, the interface height is determined by the vertical temperature distribution based on a three‐layer smoke zone model, which is an improvement of a two‐layer zone model. Thereafter, the three improved methods are applied to several typical fire cases simulated CFD to predict the smoke interface, and their applicability and reliability are verified by comparison of the smoke stratification results with the filed simulation results. Results show that the three improved methods can effectively determine the location of the three‐layer zone model's interface, and they have the ability to predict smoke interface for fires with different fire source types and ventilation conditions. [ABSTRACT FROM AUTHOR]

As many large buildings have been built worldwide recently, it is necessary to study how the acoustic environment in those buildings affects people in order to improve the acoustical comfort in them. The aim of this study is to explore the influence of acoustic environment on people in eight large-scale spaces, which are divided into three categories according to function, through grounded theory, and questionnaire. The results showed that "loud background noise," "large number of sound sources," "emotional change," "mixed sounds," and "sensible sound with certain spectrum component" were people's main evaluation to the acoustic environment in large-scale spaces. Based on respondents' perception, the influence of the acoustic environment in large-scale spaces could be classified into the following three aspects: emotional effect, influence on attention, and influence on thinking ability and behavior. Although the evaluation of the acoustic environment varied widely with the difference in spatial functions, same perception dimensions could be summarized. [ABSTRACT FROM AUTHOR]

Copyright of South Architecture / Nanfang Jianzhu is the property of South Architecture Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Currently, many airports in China are being built or retrofitted. Reducing energy consumption in airport terminals is of the utmost urgency. This paper describes on-site measurements of indoor thermal environment and air infiltration of a hub airport in winter in southwest China. Air velocity measurements with air volume balance check and thermal balance check were applied to assess air infiltration rates in terminal buildings. In unsecured halls, air infiltration rates were 0.61 air change per hour (ACH) (6.6 m3/(h m2)) and 0.28 ACH (3.0 m3/(h m2)) when space heating was on and off, respectively; while in secured piers, those two air infiltration rates were 0.42 ACH (2.6 m3/(h m2)) and 0.24 ACH (1.5 m3/(h m2)). Air infiltration consumed 66–92% of heat supplied by space heating systems, showing that winter air infiltration significantly affects indoor thermal environment and energy consumption in terminal buildings where air flows out through the doors of service walkways and open skylights on the roof. Furthermore, influences of building characteristics, space heating systems and outdoor temperatures on winter air infiltration in large space buildings were analysed. This research helps to clarify the key issues influencing indoor thermal environment and proposes solutions for energy saving in terminal buildings. [ABSTRACT FROM AUTHOR]

Most studies of neural correlates of spatial navigation are restricted to small arenas (≤1 m2) because of the limits imposed by the recording cables. New wireless recording systems have a larger recording range. However, these neuronal recording systems lack the ability to track animals in large area, constraining the size of the arena. We developed and benchmarked an open-source, scalable multicamera tracking system based on low-cost hardware. This "Picamera system" was used in combination with a wireless recording system for characterizing neural correlates of space in environments of sizes up to 16.5 m2. The Picamera system showed substantially better temporal accuracy than a popular commercial system. An explicit comparison of one camera from the Picamera system with a camera from the commercial system showed improved accuracy in estimating spatial firing characteristics and head direction tuning of neurons. This improved temporal accuracy is crucial for accurately aligning videos from multiple cameras in large spaces and characterizing spatially modulated cells in a large environment. NEW & NOTEWORTHY Studies of neural correlates of space are limited to biologically unrealistically small spaces by neural recording and position tracking hardware. We developed a camera system capable of tracking animals in large spaces at a high temporal accuracy. Together with the new wireless recording systems, this system facilitates the study of neural correlates of space at biologically relevant scale. This increased temporal accuracy of tracking also improves the estimates of spatiotemporal correlates of neural activity. [ABSTRACT FROM AUTHOR]

Abstract Currently, many airport terminals are being newly built or retrofitted. They are often designed with large open spaces, and entrances are usually open due to the continuous flow of passengers, which results in severe air infiltration. This paper investigated air infiltration in a Chinese hub airport terminal during three typical seasons by on-site measurements and computational fluid dynamics (CFD) simulations. The air-velocity method with CFD simulation was acceptable for estimating air infiltration because of the relatively constant airflow driven dominantly by stack pressure in large spaces. However, the tracer gas method was found to be unsuitable due to small differences in concentration. The air change rate varied from 0.14 to 0.56 h−1, in which the maximum value occurred in the winter daytime when space heating systems were in operation. Air infiltration caused 71% of the heat loss during the winter testing period, and 26% of the heat gain during summer. Furthermore, air infiltration in winter directly influenced thermal comfort in occupant zones (PMV = −2.58–0.55, with an average value of −1.2). Therefore, more attention should be focused on the research into air infiltration in large space buildings. Highlights • Measurements of air infiltration in an airport were performed in typical seasons. • CFD simulations and measurements were compared to evaluate air infiltration rates. • Flow patterns of air infiltration in three typical seasons are different. • Air change rates of infiltration ranged from 0.14 h−1 to 0.56 h−1. • Air infiltration caused 71% of heat losses in winter and 26% of gains in summer. [ABSTRACT FROM AUTHOR]

This paper deals with a large single space building for smoke control when a fire happens. Two hybrid ventilations are investigated, i.e. natural ventilation through a roof opening combined with mechanical suction flow, and with mechanical jet flow. Pure natural ventilation is used as a benchmark. An experimental model was reproduced as 1/10 of the prototype. Under pure natural ventilation, the roof opening played an important role in exhausting but the smoke layer height descended rapidly. Influences of mechanical flows from sidewalls on the smoke distributions were found to be evident. Large eddy full-scale simulations were performed in which grid size of the fire-domain was determined to be 0.125 m being one half of the non-fire domain. The simulation results agreed well with the experimental ones. A total of 63 ventilation cases are further simulated, and it reveals that mass flow rates of the roof opening increase with the increase of opening area ratio or discharge velocity of inlets or heat release rate but with the decrease of exhaust velocity of outlets; under hybrid ventilation of mode 4, back-flow occurs under the roof opening when the exhaust velocity reaches up to 6 m/s, and the maximum smoke temperature and the CO concentration near the door is of the lowest indicating its best advantage in controlling the fire smoke; the smoke plume is more easily disrupted by jet flow than by suction flow. This study helps to promote the design and operation of ventilation system for large and high spaces when firing. [ABSTRACT FROM AUTHOR]

Flammable gases and vapours are widely used in industrial field, which brings up the explosion risk in the large premises. In this paper, several transient experiments have been conducted in a newly built large space chamber. Sulfur hexafluoride (SF 6 ) was released in a specific place in each experiment while the space was ventilated throughout each experiment. The concentrations were measured and recorded at several points. Several parameters have been changed, namely air distribution pattern, air change rate, contaminant gas emission rate and contaminant source releasing method. The approximate accessibility of contaminant source (ACS) in different experiment conditions have been yielded with experimental data and compared. The dimensionless number ( g ' q V / D ) 1 / 3 / U i n l e t has been proposed on the basis of the passive gas criterion of ( g ' q V / D ) 1 / 3 / U to represent the magnitude of the gas gravity effect. The experiment results show obvious correlations between ACS and ( g ' q V / D ) 1 / 3 / U i n l e t at different locations. [ABSTRACT FROM AUTHOR]

Recently, occupant-centered control models have been widely discussed, with intelligent control models looking for more refined and dynamic regulation based on occupant information. This article introduced a novel method for using environmental sensors and machine learning algorithms to identify the number of occupants and activity intensity in large spaces. A multi-functional space was monitored for approximately two months using PIR, CO 2 , sound decibel, temperature and humidity sensors. To address the challenge of identifying the number of occupants in large spaces, the study proposed a non-uniformly distributed interval of occupant numbers that offsets the small fluctuations in the number of people. The study also demonstrated that PIR and CO 2 level measurements could be used to estimate the headcount interval with an accuracy rate of 84.5%. Furthermore, the study employed K-means clustering to identify low-, medium-, and high-level activities in the studied space, achieving an overall accuracy rate of 89.3%. A new metric of activity intensity was introduced to measure the activities carried out indoors, which incorporated CO 2 and sound decibel levels, PIR readings, and the number of occupants. This proposed metric was found to be appropriate for quantifying the activity intensity in the studied space. Overall, the method presented in this study provided a promising approach for enabling occupant-based control strategies that leverage advanced sensor data to optimize building service systems in large spaces. • Headcount and activity recognitions are essential for occupant-based controls. • Apply expanding occupant intervals in large spaces, not precise headcounts. • PIR and CO 2 enable accurate determination of headcount intervals in large spaces. • Estimate activity intensities using environmental factors and occupant intervals. [ABSTRACT FROM AUTHOR]

In building design, several approaches have been proposed for coupling computational fluid dynamics (CFD) and energy simulation (ES) to perform analyses of thermal environments. The unsteady analysis of thermal environments within buildings containing offices and colonnade spaces is difficult to perform using an ES that represents the space with a single mass point, owing to excessive predictive heat loss; therefore, CFD has typically been used instead. Although it is possible to divide the space into zones using ES, it leads to excessive predicted heat loss and the prediction of heat movement due to the influence of strong air currents, such as those associated with air conditioners. This behavior is observed because these zones are not detailed mesh divisions. To solve these problems, we proposed a method for calculating the ratio of heat contribution to zones that were pre-divided using CFD followed by the distribution of the total thermal load calculated by ES. In this study, we proposed a method for coupling ES and CFD, which enabled the unsteady analysis of a thermal environment in a large space and verified its accuracy.

Since the thermal environment of large space buildings such as stadiums can vary depending on the location of the stands, it is important to divide them into different zones and evaluate their thermal environment separately. The thermal environment can be evaluated using physical values measured with the sensors, but the occupant density of the stadium stands is high, which limits the locations available to install the sensors. As a method to resolve the limitations of installing the sensors, we propose a method to predict the thermal environment of each zone in a large space. We set six key thermal factors affecting the thermal environment in a large space to be predicted factors (indoor air temperature, mean radiant temperature, and clothing) and the fixed factors (air velocity, metabolic rate, and relative humidity). Using artificial neural network (ANN) models and the outdoor air temperature and the surface temperature of the interior walls around the stands as input data, we developed a method to predict the three thermal factors. Learning and verification datasets were established using STAR CCM+ (2016.10, Siemens PLM software, Plano, TX, USA). An analysis of each model's prediction results showed that the prediction accuracy increased with the number of learning data points. The thermal environment evaluation process developed in this study can be used to control heating, ventilation, and air conditioning (HVAC) facilities in each zone in a large space building with sufficient learning by ANN models at the building testing or the evaluation stage. [ABSTRACT FROM AUTHOR]

The ancient architectures of tower buildings type are representative in ancient architectures in Beijing, and compared with other types of ancient architectures, they are characterized by long distance from ground, high height of building itself, and large inner space. For the ancient architectures of tower buildings type, a proposal using floor-type fan coil air-conditioner for control of physical environment is suggested, and simulation calculation for indoor temperature field for one ancient architecture of tower building in Beijing is done using CFD software, with calculation content comprising the indoor temperature field and velocity field when the system is used in summer. The result shows that: adopting floor-type fan coil air-conditioner for summer conditions and adjusting blast amount of fan coil and blasting parameters can make air temperature agreeable and comfortable. [ABSTRACT FROM AUTHOR]

A model for indoor air vertical temperature and inner wall temperature is presented under nozzle air supply system in a large space building. Through discussion of the key parameters such as floor temperature and regional heat transfer coefficient, the floor heat transfer correction equation and modifier formula of zone heat transfer coefficient is founded. Through the summer experiment under nozzle air supply system in a large space building, the indoor air vertical temperature, inner wall temperature are tested and the modifier solving model is verified and promoted. The results show that the experiment data and the calculation results agreed well. [ABSTRACT FROM AUTHOR]

In this paper, the air flow at the nozzle side and the column side were set up in a large space. The thermal environment of the two air supply modes were compared and analyzed by using the air diffusion performance index (ADPI), the draft sensation blowing index and so on. The results show that the uniformity of indoor air temperature and velocity of the column air supply is better than the nozzle; the percentage of dissatisfaction of the indoor average air blowing is less than that of the nozzle; The ADPI value of two airflow pattern changes with the air flow. The nozzle air supply shows a decreasing trend with the increase of air flow. The ADPI of the column air supply is higher than that of the nozzle, and both of them are less than 80%. Results of this paper provide a reference for airspace organization selection and the design of large space buildings. [ABSTRACT FROM AUTHOR]

Generally, ventilation with outdoor air is used to directly remove heat in the top zone of large-space buildings to conserve energy. However, this will increase the latent cooling load because a large amount of humidity can be introduced to the interior when the outdoor air is humid. Therefore, a new method that incorporates a natural cooling water system in the top zone and does not introduce moisture is proposed in this study. The cooling tower as the source of natural cooling water and dry fan coil units (FCUs) as the terminal of removing heat were selected as an example of this new method. In order to analyze the energy saving potential of the new method, 9 cases involving different heat source distributions and cities were simulated by CFD, and 3 more cases with the traditional method were discussed. The results show that the traditional method increases the system energy consumption when the outdoor air humidity is high, and the biggest growth rate is 57.4%. But, the new method can be applied in different cities and in different heat source distributions, and can achieve a considerably high energy saving rate, ranging from 5.2% to 21.4%. The energy saving rate increases as the heat source ratio between the bottom zone and top zone decreases, because more heat can be removed by the dry FCUs. The energy saving rate varies by city, due to the different cooling water temperature. This new method will help guide the design of HVAC systems in large-space buildings. [ABSTRACT FROM AUTHOR]

A model for smoke filling in a large room was developed that considers entrainment into the horizontally spreading smoke under the ceiling. This was accomplished by incorporating a simple model for the spreading ceiling jet into the two-layer zone model. Here, the proposed model was validated by focusing on the horizontal smoke spread phase on the basis of the previous experimental data of smoke spread in a large office room. The calculated results were in good agreement with the experimental data. In addition, a case study on the smoke filling in a large room was conducted to clarify the characteristics of the proposed model. As a result, the proposed model can predict the underside of the smoke layer to be lower than the two-layer zone model. [ABSTRACT FROM AUTHOR]

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• Retractable membrane ceiling (RMC) is proposed to improve building performance. • The triple-approach controls the air velocity and solves the local thermal discomfort. • Improving thermal and energy performance using RMC is validated and quantified. • Energy reduction is obtained for air conditioning with retractable membrane ceiling. Improving the indoor thermal and energy performance of residential buildings plays a significant role in the low-carbon goals of building industry. Residential buildings usually utilize the active approaches, such as air conditioning and radiant floor. A large-space residential building that removes partial second floor can employ the retractable membrane ceiling to control building indoor performance. These active approaches can be combined to ensure thermal comfort and save energy of large-space residential buildings. Therefore, this study carries out a series of experiments to quantify the individual and combined effects of retractable membrane ceiling, air conditioning and radiant floor. The dual-approach and triple-approach experiments combine two and three from the retractable membrane ceiling, air conditioning and radiant floor. It is obtained that the membrane ceiling/air conditioning can effectively improve indoor thermal performance. The energy consumptions for air conditioning and membrane ceiling/air conditioning are 1.14 kWh and 0.89 kWh at an air temperature of 25 °C. The triple-approach experiments can solve the local thermal discomfort caused by the low air movement since the radiant floor accelerates the local air movement. The comparisons of temperature difference, air velocity and energy consumption for single-approach, dual-approach and triple-approach demonstrate that the retractable membrane ceiling is an efficient method to improve indoor thermal and energy performance of large-space residential buildings. [ABSTRACT FROM AUTHOR]

• The influence of skylight-to-roof ratios(SRRs)and skylight distribution of SIPVs on indoor daylighting quality of railway station represented large space buildings was investigated. • The most recommended value ranges of SRRs for both centralized and uniserial array distributed SIPVs has been proposed. • The SRRs based design strategies for both SIPV distributions has been concluded for Lhasa and Beijing represented solar radiation and lighting climates in China. Photovoltaic Integrated Skylights (SIPVs) have been widely used due to their unique synergistic benefits of shading and power generation. Their variable shading and light transmission properties upon varying lighting climates could aggravate the complexity of the daylighting conditions, especially when applied to large space public building skylights. In this study, Chinese cities Lhasa and Beijing were selected as representative cities for semi-transparent photovoltaic (STPV) skylight surveys corresponding to high and moderate solar radiation levels. Railway station waiting halls as the typical large space building, together with SIPVs in varying distribution modes and skylight-to-roof ratios (SRRs) have been modeled and examined. By the aid of dynamic daylighting indicator metrics and DAYSIM simulation tool, this work verified critical roles that SIPV SRRs play in indoor daylighting qualities, for both centralized and uniserial array skylight distributions. As a result, 30 % ∼ 35 % and 23 % ∼ 30 % were determined as the best value ranges for centralized SIPVs, while 16.52 % ∼ 19.27 % and 11.01 % ∼ 19.27 % were confirmed as the best value range for uniserial array distributed SIPVs, for Beijing and Lhasa accordingly. For the first time SIPV SRR based design recommendations considering both typical distribution modes had been concluded for railway station represented large space buildings, for Lhasa and Beijing represented daylighting climates or similarities. The research outcomes can assist more effective SIPV designs and daylight optimizations for such large space type public buildings. [ABSTRACT FROM AUTHOR]

Performances and efficiencies of displacement ventilation (DV) and partial ventilation (PV) for industrial halls of different configurations as well as the heat and mass transports within the industrial halls were numerically investigated. Three levels of Rayleigh number (5.8×10, 1.0×10 and 2.1×10) and two values of source contaminant flux (5 mg/s and 50 mg/s) were considered. The inlet Reynolds numbers were 2×10, 5×10, 1.5×10 and 4.5×10 for DV and 5×10, 1×10, 2×10 and 4×10 for PV, respectively. From the results, it is concluded that the above parameters have very complex impacts on the conjugated heat and mass transports. From points of view of acceptable indoor air quality and ventilation efficiency, PV at Re=1×10 with side-located sources and 65% of the supply air extracted through floor level outlets is the best choice when Ra=5.8×10. However, DVs at Re=5×10 and Re=1.5×10 with center-located sources and floor-mounted air suppliers are the best choices for Ra=1.0×10 and Ra=2.1×10, respectively. When source contaminant flux reaches 50 mg/s, local extraction as a supplement of general ventilation is recommended. The results can be a first approximation to 3D numerical investigation and preliminary ventilation system design guidelines for high-rise industrial halls. [ABSTRACT FROM AUTHOR]

Abstract: Large space buildings have their own fire characteristics. The paper builds an ideal large space building model and uses FDS software to simulate its internal smoke control effect after a fire under different conditions. The analysis shows that heat release rate and smoke exhaust volume have a great impact on smoke control effect, which can provide reference for the design of smoke control and exhaust system. [Copyright &y& Elsevier]