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The radiant systems consume less energy and provide better thermal comfort as compared to the conventional system, but the main drawback of radiant technology is inability to cater the latent load and condensation. This problem has engaged researchers to push their emphasis on Personalized Conditioning System (PCS). It forms a micro-climate region near the occupant. This study is aimed at PCS combined with a radiant conditioning system, which evaluates the performance of the PCS and compares it with different radiant cooling systems. A radiant cubicle was used to investigate the performance of the PCS for both heating & cooling modes. For heating mode, the Standard Effective Temperature (SET) was calculated with the help of thermal comfort surveys which were in a range of 23.4°C to 27.3°C. For cooling mode, four different cases compared the performance of the system which are: Conventional Air Conditioning System (CACS), Radiant Cooled Ceiling System (RCCS), Personalized Radiant Conditioning System (PRCS), and both PRCS-RCCS coupled. It was observed that PRCS alone reaches the thermal comfort criteria with low energy consumption. The energy-saving of RCCS-PRCS was achieved 38% when compared with CACS. It can be concluded that PRCS is a new step in the field of thermal comfort.

In this paper, we describe a visible-light positioning system that uses the ambient-light sensor assembly in a smartphone as a receiver for illumination signals from LED-based room lighting. After correcting for missing or inconsistently sampled data captured by the receiver, we can identify the source LEDs contributing to the received signal via Fourier analysis of its frequency distribution. Localization of the smartphone is then achieved by trilateration of the distances to the various LEDs, which are calculated from the received signal strength for each LED. Experiments using multiple LEDs were conducted to evaluate the signal reception and positioning performance of the system. We found that multiple LEDs modulated at frequencies of over 70 Hz could be correctly identified from the received signal pattern. The 90th-percentile 2D positioning errors using low frequency signals (3.951-7.902 Hz) were less than 0.21 meter for a room illuminated by four LEDs arranged in a 1-m square on the ceiling at 2.22 meters height, where the smartphone was placed parallel on the floor from 1.4 meters height. Those using high frequency signals (111.619-114.582 Hz) in the same room setting showed 50th-percentile 2D position errors of less than 0.44 meter. The position calculation was offline and not implemented on real time. Potential applications and limitations of the proposed method are discussed.

Residents tend to close the doors and windows of their residential kitchens in severe cold conditions, making insufficient outdoor air supply and aggravating indoor air pollution. In order to understand the ventilation and pollution status of the residential kitchens in a severe cold region and improve the ventilation system, this study used questionnaires, on-site tests, and Computational Fluid Dynamics (CFD) simulation to analyze a pollution and ventilation case in Shenyang, China. The method of using ceiling openings to compensate for outdoor air supply was proposed and optimized to improve air distribution in the residential kitchen. The average CO2 concentration in the breathing region, air velocity, and temperature levels in the kitchen, before and after the improvement, were compared. The results indicated that the kitchen pollution in severe cold area of Shenyang is serious, and the ventilation habit has regional characteristics. Furthermore, the overall kitchen environment including air velocity, temperature, pollutant levels, static pressure, CO2 concentration, indoor airflow fluctuation, and cooking fire were obviously improved for the ceiling make-up air cases. These findings provide a basis for improving the reasonable air distribution of residential kitchens in cold regions and for building a thermally comfortable environment.

Hydrogen is a promising energy carrier that will become competitive in the near future. The present study modeled hydrogen leaks and diffusion in an actual size underground parking garage with the numerical model validated by scale experimental data. The results show that the hydrogen concentration distributions are not uniform in the gas mixture layer along the ceiling and the initial front velocity of the gas mixture layer decays with horizontal distance from the leaking car. The vertical filling front velocity for times after 600 s remain constant in the near field but increases linearly with distance in the far field. The corner walls did not significantly affect the far-field concentration distributions and the ventilation layout with vents in the garage corners provided better hydrogen removal. These results can be used to predict the hydrogen concentration buildup in large confined spaces and to help design underground parking garage ventilation systems.

The transmission of coronavirus disease 2019 (COVID-19) has presented challenges for the control of the indoor environment of isolation wards. Scientific air distribution design and operation management are crucial to ensure the environmental safety of medical staff. This paper proposes the application of adaptive wall-based attachment ventilation and evaluates this air supply mode based on contaminants dispersion, removal efficiency, thermal comfort, and operating expense. Adaptive wall-based attachment ventilation provides a direct supply of fresh air to the occupied zone. In comparison with a ceiling air supply or upper sidewall air supply, adaptive wall-based attachment ventilation results in a 15%–47% lower average concentration of contaminants, for a continual release of contaminants at the same air changes per hour (ACH; 10 h–1). The contaminant removal efficiency of complete mixing ventilation cannot exceed 1.0. For adaptive wall-based attachment ventilation, the contaminant removal efficiency is an exponential function of the ACH. Compared with the ceiling air supply mode or upper sidewall air supply mode, adaptive wall-based attachment ventilation achieves a similar thermal comfort level (predicted mean vote (PMV) of –0.1–0.4; draught rate of 2.5%–6.7%) and a similar performance in removing contaminants, but has a lower ACH and uses less energy.

Improvement of air flow distribution, air velocity and temperature inside a mixed greenhouse dryer was numerically investigated using 3D CFD ANSYS FLUENT code. The study was performed considering six different locations of axial fans inside the greenhouse. Additional elements such as a false ceiling and front and back internal walls were included in some configurations to analyze their contribution in improving the air distribution. Numerical simulations were focused on dynamic fluid models in order to select the best configuration to achieve homogeneous air distribution and velocity among the six proposals. Then, the temperature distribution was analyzed considering the contribution of solar energy in the best-selected greenhouse configuration. Additionally, the Discrete Ordinate (DO) model was used to simulate the mechanism of heat transfer from solar radiation to the greenhouse. The results showed that installing an air recirculation system (including: axial fan, false ceiling, back and front walls), into the greenhouse can increase the air velocity in the drying chamber from 0.71 m/s to 1.5 m/s and the temperature from 315 K to 360 K, which represent an increase of approximately 111.26% y 11.11%, respectively, compared with the greenhouse without an air recirculation system. This improvement could result in the reduction of drying time and a homogeneous moisture content in dry products.

Most previous work concentrated on the thermal smoke temperature distribution in traditional single tunnel fires. However, few investigations have studied the effects of branch tunnel and longitudinal fire source location on thermal smoke temperature beneath the ceiling. In this paper, a series of experiments were performed in a 1:10 reduced scale branched tunnel to investigate the longitudinal fire location effects on the thermal smoke temperature distribution beneath the ceiling. Thirteen longitudinal fire locations and three heat release rates were considered. The main conclusions are summarized as follows: The thermal smoke temperature near the fire source is obviously different for various longitudinal fire locations, while the temperature in the area far from the fire source is basically the same. The dimensionless longitudinal thermal smoke temperature beyond 0.75 m downstream from the fire source in the main tunnel is not obviously affected by the longitudinal fire location, which can be well predicted by Li’s model. However, the attenuation coefficient is obviously larger than that in traditional single tunnel due to the existence of branch tunnel. Moreover, when the fire source moves away from the intersection region to upstream or downstream, the thermal smoke temperature in the branch tunnel shows a decrease. A modified model is proposed to describe the longitudinal temperature decay in branch tunnel taking the longitudinal fire location into account, which is reasonably well fitting with experimental results. The results in this paper are essential for better understanding of thermal smoke temperature in branched tunnel and providing references for fire safety design of branched tunnels.

El sector de la construcción es uno de los sectores que mayor impacto tiene en la economía del país; el presente trabajo busca determinar de forma exploratoria cuantitativa los parámetros más influyentes en el comportamiento térmico de una vivienda ubicada en un clima húmedo muy caluroso, para ello en el trabajo se realizó un estudio de flujo de calor en las paredes, piso y techo de una vivienda para tratar de disminuir el consumo energético del aire acondicionado y anunciarlas como eco-eficiente en la ciudad de Guayaquil - Ecuador, empleando materiales de construcción comunes de las viviendas, de acuerdo con el último censo del INEC, estos materiales son: bloque de concreto de 15 cm de espesor para paredes, concreto alivianado de 15 cm de espesor en el techo y concreto pesado de 20 cm en el piso; además, el 20% de las superficies de las paredes son acristaladas con ventanas de vidrio simple de 6 mm de espesor. Para ello se evaluarán las ganancias de calor por paredes y techos al medio día, tres horas antes y después del mediodía, para un día típico por efecto del calor sensible. Mediante la aplicación de métodos numéricos y con asistencia del software libre octave, se determina que la ganancia de color depende de la orientación de la vivienda con respecto al sol y del área más grande de pared.

Background A large share of the building energy usage corresponds to heat loss compensation and heat gain rejection. High energy consumption to provide sanitary hot water should also be considered. Methods In this paper, by introducing two scenarios, energy usage in both sections is examined in four regions (warm climates). In the first scenario, adding PCM to the vertical walls along with the ceiling, the variations of heat loss/heat gain parameters were evaluated. In the second scenario, using a solar system filled with nanofluid, the reduction in boiler energy usage was investigated. Findings The usefulness of the first scenario depended on the PCM melting temperature. PCM 24 performed better in warm climates. In the first scenario, the energy-saving was in the range of 620–6600 kWh year for warm climate. Although the first scenario was not always useful, the second scenario always reduced the boiler energy usage. The use of collectors filled with Al2O3/water led to energy-saving within the range of 3400–4500 kWh year .

Funding Information: The work was supported by the National Key Research and Development Program of China (No. 2016YFC0802900) and Graduate Research and Innovation Projects of Jiangsu Province (KYCX21_2446). Also, authors would like to thank the China Scholarship Council (CSC) for the financial support of the first author (Grant No. 202006420046). Publisher Copyright: © 2021, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature. In order to reveal the evolution of ceiling jet temperature characteristics beneath curved ceiling in two-dimensional view, experimental and theoretical studies were conducted to analyze the vertical temperature profile and longitudinal temperature attenuation beneath a curved ceiling of a semicircular tunnel. The temperature profile was first measured from experiments carried out in the model-scale semicircular tunnel. The relationship between temperature and the horizontal positions is described by an empirical model. A formula describing the thickness of the thermal boundary layer is proposed, based on the vertical distribution of smoke temperature. An engineering model for the longitudinal attenuation of the gas temperature with different fire plume types at impingement region is established in terms of conservation equations. After validation, model predictions show a good agreement with trend proposed by former literature and the relative error of prediction is found to be within 10%. Two-dimensional prediction for temperature profile beneath semicircle ceiling centerline was proposed. It was noted that two-dimensional prediction model could predict majority of measured data within 20% relative error even though some fluctuation, which could be applied to the fire protection engineering in semicircular tunnel.

Within the field of textile construction, textiles are traditionally used either as decorative elements in interior design or as flat textiles in tensile-stressed lightweight constructions (roofs, temporary buildings, etc.). Technical textiles made of glass or carbon fibers are now also used as steel substitutes in concrete construction. There, flat textiles are also used as lost formwork or shaping semi-finished products. Applications for 3D textiles and in particular spacer textiles have so far only been investigated as part of multilayer constructions in combination with other elements. Otherwise, there are no studies for their application potential in the roof and wall areas of buildings and as a starting structure for opaque and translucent components. The two research projects presented here, "ReFaTex" (adjustable spacer fabrics for solar shading devices) and "ge3TEX" (warp-knitted, woven and foamed spacer fabrics) illustrate for one thing the possibilities for using 3D textiles for the construction of movable and translucently variable solar protection elements in the building envelope. Otherwise they show how 3D textiles in combination with foamed materials can be transformed into opaque, lightweight, self-supporting and insulated wall and ceiling components in the building envelope. Both projects are designed experimentally and iteratively. The results are compared in a qualifying manner, the aim being not to quantify individual measured variables but to explore the development potential of textile construction for sustainable future components and to realize the first demonstrators. In the ReFaTex project, 1:1 demonstrators with different movement mechanisms for controlling the incidence of light were realized. In the ge3TEX project, 1:1 demonstrators made of three different textile and foam materials were added to form new single-origin composite components for ceiling elements. Both projects show the great application potential for 3D textiles in the construction industry.

The article presents a case study on the impact of thermal rehabilitation of buildings heat demand. In order to reduce specific heat consumption and, in general, heat consumption for heating and hot water preparation, measures are needed to rehabilitate and modernize the thermal protection of buildings and heating and hot water installations. The present study aims to determine the influence of thermal rehabilitation of buildings (insulation of exterior walls - in this case) making for this purpose a comparison of the values of thermal requirements before and after the thermal rehabilitation process for a building. Regarding the thermal insulation used in the case study, expanded polystyrene with a thickness of 10 cm was used for the exterior walls and mineral wool for ceiling. The main purpose of the work is to highlight the importance of thermal insulation of buildings mainly in terms of reducing energy costs and maintaining thermal comfort in homes

В роботі було досліджено альтернативні види систем формування клімату на основі таких видів систем охолодження як: адіабатичне охолодження; холодна стеля; абсорбційна холодильна машина з використанням броміду літію; система з використанням елементу Пельтьє. Запропоновано та розроблено схему, яка враховує недоліки розглянутих систем. Запропонована система має просту конструкцію, більш екологічна, в неї відсутній холодоагент. Розраховано кількість елементів Пельтьє необхідну для формування заданої температури в приміщенні. Розробка альтернативних систем охолодження дуже актуальна проблема на сьогоднішній час. У житлових приміщеннях набув широкий попит на кондиціонери з використанням фреону у якості холодоагенту. Дані системи не є надійними через те, що є ризик витоку фреону. Також є проблема в тому, що кондиціонер є осередком підвищеної вологості, що в свою чергу спричиняє розмноженню бактерій та грибків. Разом з посиленням санітарних вимог до житлових приміщень та тих приміщень де перебуває людина та заборонами використання старих різновидів фреонів змусили науковців та виробників шукати нові, більш екологічні, види охолодження приміщення без використання фреонів. Серед них це: використання води та її розчинів в якості холодоагентів; використання різниці температур навколишнього середовища; теплонасосів заснованих на ефекті Пельтьє. В результаті досліджень було встановлено, для охолодження приміщення краще використати елемент Пельтьє, так як він екологічний (відсутні викиди CO2, CO, CFH3, CFClH2), відсутні механічні деталі. Для охолодження приміщення площею 10 м2 потрібно близько 8 шт. Для точного керування системою краще використовувати точні датчики температури. Отримані дані є корисними та важливими: доведено, що система з використанням елемента Пельтьє може працювати на генерацію холоду; запропонований розрахунку є універсальними, тому , що має можливість розрахувати потужності елементів Пельтьє. Використання елементу Пельтьє дозволить використати силу сонця для зменшення негативних впливів на людину, зокрема вплив високої температури.

A series of hydrogen explosions were conducted in a real scale container with and without vents. The effects of hydrogen concentration, ignition location, obstacles on the vented hydrogen-air explosions were investigated. Hydrogen explosions with concentration of 12% and 16% were conducted in constant volume container, and the maximum peak overpressure can reach 45 kPa and 175 kPa, respectively. During the vented hydrogen explosions, three overpressure peaks generated by the vent rupture, Helmholtz oscillation, and the thermo-acoustic-vibration coupling, respectively, were recorded. The maximum peak overpressure is about several kilopascal, the pressure reduction can reach 97.1% by comparison with peak overpressure developed in closed container. The obstacles change the way that the flame travel inside the container, and resultantly the flame propagates vertically and increases the flame area, which promotes the reaction and increases the peak overpressure, which also increases with the hydrogen concentration. Three engineering models used to depict the relationship between the vent area and the maximum reduced explosion pressure were assessed. Results show that the these models over-predict the maximum reduced explosion pressure for high-reactivity mixtures. However, for low reactivity, the Molkov’ models show a scatter while the NFPA68 gives a better prediction.

Modular steel buildings (MSBs) are an innovative form of prefabricated buildings with many advantages related to the factory-manufactured construction process. However, technical issues in the global stability design remain ambiguous and induce either unsuitable or uneconomical results without understanding the effect of intermodule connections appropriately. In this study, one practical theoretical equation to determine the buckling length factor for the sway-permitted MSB was derived from a sub-assembly considering pinned or rigid inter-module connections. A large number of finite element models were then used to numerically validate the effectiveness of the theoretical equation and explore the main influencing factors including both intermodule connections and height-to-width ratios. Results indicated that the intermodule connections should be carefully considered when the floor beams are obviously larger than ceiling beams, and theoretical results can be accurate enough when the height-to-width ratios remain within 3.0. Moreover, the second-order analysis method for MSB was also performed by using nonlinear buckling analyses and then compared with the buckling length method to verify the previous findings. Finally, the criterion in selecting the proper stability design procedure for MSB was discussed in depth.

Performance of visible light communication systems which is encoded using turbo product codes is studied in this article. It is the first time to show the effect of turbo product codes in these systems. We chose ceiling bounce model since its accuracy with the practical measurements is proved. Our simulations are carried out in two different link distance and two different data rates. Encoder parameters are selected according to the code rate. This way, meaningful comparison can be made among the results considering distance, data rate, and code rate. Our investigations infer that using turbo product codes, higher data rate is achieved where link distance is the same. Similarly, it can be reached higher link distance when data rate is set to a constant value.

One of the deficiencies of using Phase Change Materials (PCMs) is the low conductivity, therefore, increasing the heat transfer from and to the PCM remains a challenge. The exposed surface area of ...

In this paper, a method to model a tunnel using lidar points is presented. The data used was collected using Leica Pegasus Two Ultimate with a Z+F 9012 Profiler mounted on a mobile platform. The tunnel was approximately 151 m long. Visual inspection of a cross-section of the tunnel showed two rail tracks supported on ballast and sidewalks along both sidewalls of the tunnel. The walls and the ceiling of the tunnel were made of five planar surfaces. The tunnel alignment was straight, without any horizontal or vertical curves. The bearing of the central axis of the tunnel was N12.2oW. The following methodology was developed to model just the planar surfaces of the tunnel by excluding the rails, ballast, sidewalks, powerlines, and other accessories. The entire methodology was divided into three broad parts. In the first part, a model cross-section was created. Since the design plans of the tunnel were not available, the model cross-section polyline was created using mean tunnel dimensions from random cross-section points. The model cross-section consisted of the walls and the ceiling of the tunnel. Points were placed at every 1 cm along the model polyline. Six of the model points that represented the shape of the tunnel were selected as salient points. The lower-left salient point was considered as the seed point. In the second part, to define a reference axis of the tunnel, an approximate centerline was manually defined by selecting points at its start and end. Lidar points within 1 m at the start and the end of the tunnel were modeled using the model points to determine the centroids. The reference axis was determined by connecting the centroids at the start and the end of the tunnel. In the third part, the tunnel points were sliced along the reference axis at 5 cm intervals. The model cross-section was matched to points within each tunnel slice using a three-stage approach. In the first stage, the pattern of salient points was matched to the tunnel points by placing the seed point at every tunnel point location. The distances between salient points and their nearest tunnel points were calculated. Ten sets of tunnel points with the least differences to the salient points were shortlisted. In the second stage, a dense point-to-point matching was performed between the model and sliced tunnel data at the shortlisted points. The shortlisted point location with the least difference between the tunnel and the model points was considered as a match. At this point, the model points were hinged to the tunnel points at the seed point location. Hence, in the last stage, a six-parameter affine transformation was performed to match the model points to the tunnel data. The transformed model points at every 5 cm of the length of the tunnel were considered as current shape of the tunnel.

Accidental fires result in extensive loss of property, damage to the environment and a large number of fatalities every year. When fuel collects in the form of a pool and burns, it is termed a pool fire. Pool fires may burn in isolation – Non-interacting or as Single Pool Fires (SPFs) – or flames from multiple pool fires may interact with each other and burn in what is termed as Multiple Pool Fires (MPFs). Even as single pool fires (SPFs) are difficult to control, interacting flames due to multiple pool fires (MPFs) are even more difficult to extinguish. Compared to SPF, MPFs tend to have much higher flames and are reported to have extraordinary thermal intensity. Accidental pool fires in warehouses, commercial and residential buildings may interact, giving rise to interacting pool fires (MPFs). The commonly used technique to suppress fires in enclosures such as warehouse, commercial or residential buildings is to use sprinklers. Hence, this study reports the numerical simulations performed to analyse the effectiveness of water-mist sprinklers in extinguishing MPFs. The related CFD coding and simulations were performed using Fire Dynamics Simulator (FDS), FDS tools like Pyrosim (pre-processor) and Smokeview (post-processor) packages. The effect of the ratio of the separation distance between the pools (S) to the diameter (D) on the overall fire suppression efficiency of the water-mist sprinkler as a function of the water mist flow rate, the height of the ceiling, and sprinkler particle size are vigorously analysed in this work. The analysis presented in this article will mainly help to resolve problems associated with the effectiveness of mist-sprinkler in warehouse fires regarding process safety viewpoint.

In the historical period, different mosques were built in the Anatolian side, the differences in size, typology and style were affected by the climate conditions, cultural and social aspects, availability of materials and the construction techniques of the region they were built in. The ceiling structure, which is the most influencing factor for mosque acoustics, is designed with either curvilinear elements or a flat ceiling for mosques. In the context of our case study, the eight historical mosques in Turkey, with different materials and types of ceiling structures, are investigated in terms of acoustical characteristics in the main prayer hall. Acoustical data are collected by measurements to reveal how the formal differences and material change in ceiling structures affect the acoustic environments of mosques with similar volume. Distribution of acoustical parameters and the suitability of the values obtained through measurements are compared to reflect the effect of architectural features on the acoustical characteristics of the prayer hall.

To analyze the influence of a curved ceiling and fire location on the combustion characteristics in a utility tunnel, the burning rate and temperature profile produced by a pool fire beneath a curved ceiling were investigated experimentally and theoretically. The results showed that oxygen supply and heat feedback from the surrounding form a competitive mechanism, determining the evolution of the burning rate. A qualitative analysis was performed to elucidate this competitive mechanism. With the fire source moving close to the sidewall, the positive influence from the heat feedback is is gradually compensated for by the negative influence from oxygen supply limitation. Moreover, it was inferred that the magnitude of decline of the burning rate near the wall has a positive correlation with heat release rate of the fire source. A characteristic inclined angle was defined to replace the changing angle of the curved ceiling along the ceiling jet path. Based on the definition of the characteristic ‘inclined angle’ concept, the relationship between the temperature profile beneath the curved ceiling centerline, tunnel height and horizontal position from fire source was unified by an empirical model. The maximum temperature delay beneath the curved ceiling centerline produced by the pool fire was analyzed by radial flow and one-dimensional flow. The proposed models for radial flow and one-dimensional flow were validated and could effectively predict the maximum temperature delay, which can be applied in utility tunnel’s fire protection engineering.

The objective of this study is to investigate critical velocity and smoke maximum temperature beneath the ceiling in the connected area of branch tunnel with varying fire locations. The fire sources were located in the divergent connected area of the branch tunnel, to imitate traffic accidents near the branch point. A 1/20 scale model branch tunnel was built including main line before branch, main line after branch, and ramp. Experimental tests and numerical simulations were performed to explore smoke movement characteristics with longitudinal ventilation. The results showed that the enlarged cross-sectional area in branch tunnel caused the shortening of the back-layering length, and a modified model of back-layering length was proposed. The higher tunnel height in this work affected the critical condition of large fire; it caused a larger transition point of dimensionless critical velocity. A revised model was proposed for the maximum temperature rise of tunnel fires in the connected area of branch tunnel. The critical velocity kept unchanged when the branch angle increased from 0° to 20° because there is little change in the longitudinal smoke temperature. As the local tunnel width of fire source was increased, the required critical velocity was increased while the local effective velocity kept nearly the same.

Introduction.The problem of timely activation of fire sprinkler systems is highly relevant for effective fire suppression before the critical moment, when calculated values applied to extinguish the fire, become ineffective. A number of works address the problem of effective application of the fire sprinkler system to Class A fires. The application of such methods to Class B fires has not yet been considered.The model simulating a fire in a room with an automatic fire extinguishing system.The response time assessment model, developed by the co-authors for an automatic water-consuming fire sprinkler system, allows to identify the velocity of flame spreading over the surface of an HFL/CL spillage and the temperature rise rate in the ceiling area in the case of a B class fire.A sprinkler is triggered by the bulb bursting caused by the thermal effect produced by the ascending convection flow.A model has been developed to determine the response time of a fire sprinkler system exposed to the effect of a heat flow, caused by the Class B fire, on a heat-sensitive sprinkler bulb.Activation of a fire sprinkler system by the rate-of-rise heat detector.A model, designated for determining the activation time of a rate-of-rise heat detector, was developed.Examples.A number of examples, illustrating the response time of traditional, deluge, and forced launch fire sprinkler systems, are provided in the article.Conclusions.The obtained formula allows to quickly check the applicability of different types of fire sprinkler systems to ensure the effective protection of premises in which class B fires may break out.

ITAP panels - interior thermally active panels with an integrated active surface in an innovative way combine existing building and energy systems into one compact unit, and thus create combined building and energy systems. These are building structures with an internal energy source. Low heat losses, respectively, thermal gains predestine for energy-efficient buildings the application of low-temperature heating/high-temperature cooling systems such as large-area floor, wall, and ceiling heating/cooling. The main benefit of ITAP panels is the possibility of unified and prefabricated production. At the same time, they represent a reduction of production costs due to their technological process of production, a reduction of assembly costs due to a reduction of steps during implementation on the construction site and a reduction of implementation time due to their method of application.

This article addresses the task of mobile robot localization for indoor navigation. In this article, we propose a novel indoor localization system based on separated sonar sensors, which can be deployed in large-scale indoor environments conveniently. In our approach, the separated sonar receivers deploy on the top ceiling, and the mobile robot equipped with the separated sonar transmitters navigates in the indoor environment. The distance measurements between the receivers and the transmitters can be obtained in real time from the control board of receivers with the infrared synchronization. The positions of the mobile robot can be computed without accumulative error. And the proposed localization method can achieve high precision in the indoor localization tasks at a very low cost. We also present a calibration method based on the simultaneous localization and mapping to initialize the positions of our system. To evaluate the feasibility and the dynamic accuracy of the proposed system, we construct our localization system in the Virtual Robot Experimentation Platform simulation platform and deploy this system in a real-world environment. Both the simulation and real-world experiments have demonstrated that our system can achieve centimeter-level accuracy. The localization accuracy of the proposed system is sufficient for robot indoor navigation.

It is critical to comprehend the safety aspects of hydrogen fuel cell vehicles (FCVs) in semi-confined and confined environments. The hydrogen jet fire is a key hazard resulting from coincidental hydrogen release from onboard storage followed by ignition. The rise in temperature and depletion of oxygen inside the tunnel may cause calamitous debacles. In this study, comprehensive computational fluid dynamics (CFD) simulations were designed to understand the interactions of multiple hydrogen fires in a confined environment. CFD simulations for hydrogen and liquefied petroleum gas (LPG) jet fires were conducted inside a reduced scale model tunnel. The model is initially validated against the experimental data for a single LPG fire scenario. A parametric study was then made to understand the impact of the fire location in the tunnel and the ventilation velocity. The results show an increasing-decreasing trend in the temperature over the two fire sources before the temperature reaches a quasi-steady state for the cases without ventilation speed. However, in the presence of ventilation velocity, the temperature rises are seen until a quasi-steady-state is reached. The vicinity of the two flames in the tunnel influences ignition proficiency, dependent on the heat feedback enhancement and air supply restriction instruments. A temperature drop was seen at the ceiling as we move along the passage length. The ventilation velocity influences the proportion of fuel and oxygen, driving the burning proficiency to either increase or decrease. The overall ceiling temperatures were seen to reduce in the presence of higher ventilation velocity. In conclusion, for hydrogen and LPG fire interaction, a distinction in the ceiling temperature pattern was seen between the two because of the disparity in the emissivity of the two fuels.

Hard concrete roofs cause excessive heat gain impacting thermal comfort in buildings. Terrace gardens promoting greening at higher levels of built structures are seen as one of the key mitigating strategies for modifying building microclimate and improving urban health. We have undertaken a research project to quantitatively assess the value of a terrace garden in a residential scale. A garden patch of about 15 m2 in area, a typical size available in most urban terraces is developed. Surface temperatures are measured over a period of 15 months between July 2018 to January 2020 using four thermocouple sensors, placed within and outside the garden bed, on and below the roof. We compare the thermal performance of the terrace garden across years, seasons, time of the day, presence or absence of garden bed and type and height of vegetation. The surface temperature data was found to correlate well with the ambient air temperature values. The results show that the terrace garden moderates and stabilises the ceiling temperatures and reduces it by about 2–3 °C in winter months and 5–7 °C in hot summers. The garden also provided nearly 400 g of fresh monthly vegetable harvest per m2 of garden. Further, the cooling impact of the terrace garden with natural, tall, wild vegetation is higher as compared to planted vegetation. The study demonstrates a sustainable approach to terrace garden design at residential scale through quantified dual benefits of temperature control within buildings and urban farming.

Objectives Increased use of small affordable alarm sensors with logging or network capabilities has improved the ability to monitor exposure. The large datasets generated from these monitors calls for development of a computer algorithm to assess these data. Methods We examined 88 time series of hydrogen sulphide (H2S) from wastewater works previously used for developing the exposure index. The time series covered 331 h, where 16 h had readings different from zero. Results The developed algorithm reproduced the manual assessed index almost perfectly (linear regression β = 1.02, R2 = 0.97, P < 0.001). Time-weighted average (TWA) values of the 88 time series showed a mean value of 0.04 ppm (range 0.0–0.9). The mean index value was 18 (range 0–337), with a good linear fit (β = 0.002, R2 = 0.93, and P < 0.001). The index gave us a better resolution and basis for risk assessment than the TWA, and managed to combine evaluation of TWA and exceedance of ceiling value in one number. Conclusions As long as peaks above ceiling value occur, we find alarm tools with an H2S sensor to be an essential personal protective equipment against H2S. The proposed method has been verified, and it removes some common human errors in graph evaluation. Use of the index is a possible way of quantifying risk level in exposure to H2S in one single number and provides better understanding of the risk of exposure, as it eases the analysis and evaluation of large numbers of time series.

The present study experimentally investigated the heat flux distributions produced by rectangular fire sources under unconfined inclined ceilings, which have not been quantified in previous studies. The source–ceiling heights, heat release rates, inclination angles of the ceilings (from 0 ∘ to 20 ∘ ), and aspect ratios of the rectangular burners (from 1 to 10) were considered comprehensively for a total of 160 sets of test conditions. The results showed that the ceiling heat fluxes in the upstream and downstream areas decreased with an increase in the radial distance. However, with an increase in the ceiling's inclination angle, the attenuation rate of the upstream ceiling heat flux decreased, while the attenuation rate of the downstream ceiling heat flux increased. The upstream and downstream heat flux distributions beneath the ceiling under all the experimental conditions could be well described by a modified model. This study provided quantitative data and a basic understanding of the heat flux distributions under an inclined ceiling induced by different rectangular-source fire impingements, which were essentially different from other previously reported ceiling jets.

Automated stocker system is widely used in semiconductor and liquid crystal display (LCD) industries for handling and storage of valuable wafers or glass panels. Massive front opening unified pods (foups) containing wafers, or cassettes storing glass panels, are placed in shelf stockers during manufacturing. Although several preventative measures have been taken, during the past earthquakes, substantial financial loss from the industries were reported, and one of the main causes was attributed to collision of the foups or cassettes and shake off from the shelfs. This paper proposes a methodology of incorporating viscous fluid dampers into the stokers to mitigate their seismic response. Unlike conventionally been done in buildings where dampers are placed between adjacent stories, it is proposed to install dampers in between the ceiling and top of the stocker. Such configuration utilizes the large velocity at the stocker top under vibration, resulting in smaller damper size, and enables a leverage mechanism that requires smaller damper force to resist the stocker’s vibration. Both shake table tests and simulation of a full-scale stocker under realistic earthquakes have been conducted. Results indicate that both displacement and acceleration responses of the stocker can be significantly reduced, and dynamic response of the stocker under seismic excitations can be well predicted.

Heat release rate (HRR) is most important factor in the tunnel fire. Therefore, an accurate understanding of the relationship between tunnel fire and HRR is required. The HRR of a pool fire is related to the heat feedback mechanism. Heat feedback is mainly affected by the flow around the fire source. However, considering the flow characteristics that depend on the tunnel slope is insufficient. Therefore, in this study, the effect of flow with respect to the tunnel slope on the heat feedback was analyzed with an experimental method. The experiment was conducted with a reduced-scale shallow underground tunnel. The slope of the tunnel was limited to 0° to 7°, which corresponds to the construction standard. The ceiling jet and entrained-air flow were affected by the pool diameter and tunnel slope. Owing to the effect of the air entrainment, the ratio of the re-radiation heat flux incident on the fuel surface decreased linearly with increasing tunnel slope. Moreover, the re-radiation and re-convection ratios of the tunnel slope and pool pan size showed linear trends. Based on the analysis of the heat feedback mechanism, the empirical correlation for the effect of the tunnel slope on the HRR can be presented in terms of the re-radiation/re-convection fraction.

In tunnel fire, smoke is a great threat to successful emergency escapes, and its spreading patterns at high altitude tunnel may differ. Therefore, the impact of ambient pressure on the stability of smoke layers and maximum smoke temperature under ceiling in ventilated tunnels were investigated in this study. Results show that the temperature of smoke layer is negatively correlated with the longitudinal velocity and ambient pressure. Besides, the influence of longitudinal velocity at different ambient pressures on the shear velocity between the smoke and air layers was further studied. Using Richardson number ( Ri) and Froude number ( Fr), smoke flow can be classified into three patterns, namely stable and obvious smoke stratification ( Ri>3.2 or Fr 0.53). Furthermore, a model has been developed to predict maximum smoke temperature under the tunnel ceiling, which agrees well with previous studies at standard atmospheric pressure. The results of the present work provide information for tunnel structure protection and safe evacuation in fire accidents at different ambient pressures.

This paper studied the effect of lateral smoke extraction on the transverse temperature distribution and maximum smoke temperature beneath the ceiling. The experiments were conducted in a reduced model tunnel (1:8). In the experimental study of optimal aspect ratio of the smoke extraction vent, a series of experimental conditions were considered. Keeping the same area of vents, four kind aspect ratios were set (n = 1, 2, 3, and 4). In experiment investigation of ceiling maximum smoke temperature, under the best vent aspect ratio n = 3, four fire heat release (50 kW, 60 kW, 70 kW, and 80 kW) rates were considered. The experimental results showed that the lateral smoke extraction system will affect the transverse temperature distribution, the transverse temperature distribution curve shows good stratification phenomenon, and the maximum temperature point will offset to the direction of the lateral extraction vent. The data of the maximum temperature under different test conditions were analyzed, and the influence factors of lateral smoke extraction were considered. Finally, the correlation of the maximum smoke temperature under the influence of lateral smoke extraction was proposed.

The plane has become a convenient method of transportation. The main idea of aviation in the 21st century is the safety of passengers and crew, but the human is always inclined towards comfort. The structural and parametric analysis of the long-haul aircraft development made it possible to form the concept of the fuselage layout with capsule accommodation of passengers. By adding the third axis to the dimension of the aircraft expressed in take-off mass, it clearly showed the ultimate dimension of the aircraft, expressed by modern infrastructural constraints. The histogram of the distribution of flights between the largest airports in the world that can operate with long-haul aircraft was showed. The distribution of large airports was characterised by the demographic factor. The proposed variant of the capsule accommodation, designed for the Boeing 777-200LR, can be installed in other passenger airliners with a ceiling height of at least 2.1 m. Analysis of alternative options for the layout of the passenger compartment allows us to state: with a flight range of more than 8 hours, the flight is comfortable only in business or first classes. The proposed two-story capsule placement allows providing the layout with first-class seats in a given cabin.

The purpose of the work is to study the development of concepts and technologies for the manufacture of ceiling fixtures to light the interior of buildings – office, public and administrative ones, etc. It is known that fluorescent lamps have long been used for interior lighting. Massive diffusers made of matte polycarbonate sheets were used to smooth the light intensity curve of such luminaires and bring it to the cosine light distribution. Due to the matte coating of the diffuser, the luminous part of the light fixtures acquired, with a fairly good approximation, the properties of an equally bright surface. Such surfaces are known to have a cosine light distribution and are very convenient for lighting. In the early 2000s, the problem of energy saving worsened, which led to a significant reduction in the number of luminaires of this type. These changes have also affected the approaches to the design of indoor light fixtures. The major difference of the new modifications of fluorescent fixtures is the absence of a matte reflector, which is very uneconomical in terms of energy saving, since it significantly decreased the luminous flux. The refusal to use the diffuser led to the emergence of fluorescent fixtures with a specular reflection system and shutters, which limited the dazzling effect of such lamps. However, with the parallel development of LED technology, the concept of choosing a light source in indoor lighting fixtures began tochange. In grille fixtures, LEDs were gradually replacing fluorescent ones. Nowadays, manufacturers' websites offer a fairly wide selection of LED fixtures. They differ in the price, quality of LEDs used, design and technological solutions. Recently, the volume of production and range of LED light bars has been increasing. The article presents an attempt to consider which fixtures offered on the modern market are the most balanced in terms of engineering solution in the context of lighting, operational, pricing, technological and certification characteristics. Based on the analysis of fixtures of different types and modifications, the authors concluded that the most optimal engineering solution is ceiling LED light bars and developed a method of their design and certification.

Objective: The purpose of this study is to derive design dimensions for each spatial factor based on subjective satisfaction evaluation using variable UAM (Urban Air Mobility) Mockup and to suggest guidelines for UAM internal space design. Background: Urban Air Mobility (UAM), which enables transportation of cargo and passengers in urban areas, has been proposed as a solution to the problem of economic loss and environmental pollution caused by ground transportation worldwide. Despite the active development in many companies such as UBER, Airbus, and Hyundai, the research on UAM internal space design is very insufficient compared to the research on UAM’s technical factors and the design guidelines for each internal space factors based on user satisfaction are needed. Method: In this study, 100 adults in their 20s were tested by variable UAM Mockups based on existing design guidelines for aircraft and helicopters and 5 to 95%ile of body dimensions presented in Size Korea. As independent variables, Seat Angle (0~30°), Seat Width (390~470㎜), and Seat Height (350~450㎜) were selected, and as dependent variables, Subjective Rating Level and Space/Seat Satisfaction for Seat (front/rear) Distance, Side Allowance Distance, and Ceiling Height. Subjective Rating Level for each factor was measured in three categories: First Uncomfortable Distance (FUD), Lowest Acceptable Distance (LAD), and First Comfortable Distance (FCD), and a survey of Space/Seat Satisfaction was conducted whenever each point was reached. Results: As a result of the experiment, the highest satisfaction with Space/Seat Satisfaction was shown at the Seat Angle 20°, Seat Width 450, 470㎜, and Seat Height 400㎜. A guideline for each Subjective Rating Level (FUD, LAD, FCD) for Seat (front/rear) Distance, Side Allowance Distance, Ceiling Height are derived. Conclusion: It is assumed that the appropriate design guidelines and methods derived for each Subjective Rating Level (FUD, LAD, FCD) by combining seat design factors and cabin space design factors can be used not only for UAM but also for vehicle and aircraft internal design. Application: If the Subjective Rating Level (FUD, LAD, FCD) is appropriately considered, it can be used as a guideline to satisfy both user satisfaction and optimization of UAM internal space design.

This paper presents an experimental study to investigate sustainable alternative ceiling boards using PKS and BS. The ceiling boards were prepared by mixing BS/binder, PKS/binder, and PKS/BS/binder at different ratios of 20/80, 40/60, 60/40, and 80/20 and represented as samples (A1, A2, A3 and A4), (B1, B2, B3 and B4), and (C1, C2, C3 and C4) respectively. The samples were cast by flat press process in rectangular sheet shape mould of 187 mm × 125 mm × 3 mm, cut into specimen sizes of 30 mm × 40 mm then tested for dry shrinkage, water absorption, apparent porosity, bulk density, flaking, and hardness properties. The morphology of the samples was examined using SEM. Results of the analysis show that irrespective of the filler loadings the properties of PKS / binder particularly at 20/80 ratio ‘‘B1” displayed better dry shrinkage of 3.7%; water absorption of 12.4%; apparent porosity of 15%; bulk density of 2.3 g/cm3; flaking of 0.05 g and hardness of 57.6 Hv which approximates those of the conventional specimen with better physical properties compared to BS/binder at 20/80 ratio ‘‘A1” and PKS/BS/binder at 20/80 ratio ‘‘C1”. These results, therefore, suggest that PKS at 20/80 ratio with improved strength could be used as a sustainable alternative in the production of ceiling boards.

During the current SARS‐CoV‐2 and tuberculosis global pandemics, public health and infection prevention and control professionals wrestle with cost‐effective means to control airborne transmission. One technology recommended by Centers for Disease Control and Prevention and the World Health Organization for lowering indoor concentration of these and other microorganisms and viruses is upper‐room ultraviolet 254 nm (UVC254) systems. Applying both a material balance as well as some nondimensional parameters developed by Rudnick and First, the impact of several critical parameters and their effect on the fraction of microorganisms surviving UVC254 exposure was evaluated. Vertical airspeed showed a large impact at velocities 0.05 m s−1. In addition, the efficacy of any upper‐room UVC system is influenced greatly by the mean room fluence rate as opposed to a simple volume‐ or area‐based dosing criteria. An alternative UVC254 dosing strategy was developed based on the fluence rate as a function of the UVC254 luminaire output (W) and the square root of the product of the room volume and the ceiling height., During the current SARS‐CoV‐2 and tuberculosis global pandemics, public health and infection prevention and control professionals wrestle with cost‐effective means to control airborne transmission. One technology recommended by CDC and WHO for lowering the indoor concentration of these and other microorganisms and viruses is upper‐room ultraviolet 254 nm systems. The design cycle for implementation of UVC systems starts with UVC dosing in the space and moves through many other steps before installation. This paper describes an alternative dosing strategy to the recently proposed volumetric dosing criterion.

In tropical countries, there is a need for air conditioning systems, especially for high-rise buildings to provide comfort for their residents. For this reason, it is necessary to plan an air conditioning system using a ceiling duct with a VRV / F (Variable Refrigerant Volume / FLOW) system setting so that the load and capacity are appropriate and more efficient. In calculating the cooling load, starting from the sensible load and the load, and calculating the size of the ducting. The research method used to plan an air conditioning system using a ceiling duct with VRV / F system settings is the observation method by taking the required data. Perform calculations and analysis with the data obtained. So that after planning the total load on the 5th floor = 270,752.79 Btu / hr (79.3498kW), the 6th floor = 280,568.37 Btu / hr (82,227 kW), and the 7th floor = 229,690.66 Btu / hr (67.3157kW). The size of the ducting supply used is: Height = 75mm-450mm, Width = 75mm - 450mm and the size of the ducting return used is Height = 75mm-450mm, Width = 75mm-450mm. From the planning results, it is determined that the air conditioning system uses a ceiling duct system with VRV / VRF system settings. The advantages are Easy Maintenance, high reliability, large capacity use, space-saving design, different indoor units in one system, and using R410 type refrigerant.

Although utility tunnels act as an innovative technique for the sustainable development of city’s utilities and limited underground space today, the fire issues in this type of tunnel should be carefully treated as they are different from traffic tunnel fire scenarios. In order to propose an easy-to-use two-dimensional (2D) temperature estimation methodology that is helpful to the designers, operators and firefighters, the temperature distributions and ceiling jet thickness (the vertical distance from the ceiling to where the temperature within the fire-induced smoke flow drops to half of its maximum at a certain location) were investigated with full-scale fire tests in a utility tunnel. The vertical temperature distributions were represented as a normalized single convex-concave profile. Self-similarity was confirmed and three types of similarity profiles were found. In order to correlate the inner boundary layer region and outer region of these ceiling jet flow profiles, a series of mathematical functions combining a power function and Gortler’s error function were employed. Furthermore, the ceiling jet thickness was found to vary as a power function with the longitudinal distance, rather than being a constant as previous research suggested. The vertical distribution model, the ceiling jet thickness model and the longitudinal temperature decay model were combined into a framework to empirically estimate the 2D thermal environment generated by strong fire plumes in utility tunnel’s fire protection engineering practice.

Introduction. Сases of ineffective activation of automatic sprinkler fire-fighting systems (AFFS), designed pursuant to current standards, have made it necessary to address the following three issues: a) identification of reasons for ineffective activation; b) examination of AFFS systems to ensure their successful activation in case of fire; c) making a list of recommendations for AFFS designers. These issues can be resolved with reference to Appendix B to new SP (Construction Regulations) 485.13130.2020.Maximal critical height of sprinkler placement. Models of fire development were used to design the roof height limit and the AFFS bulb heating time. If the ceiling height exceeds the limit value, sprinklers cannot be activated in a timely manner. This leads to delays in the AFFS activation, and, as a result, the fire area exceeds the one safeguarded by the sprinkler.Acceptable sprinkler height. The analysis of fire scenarios and bulb heating models allows to more accurately project the feasibility of timely AFFS activation. This, in turn, allows to solve the three above listed problems.Using a differential heat detector to activate sprinklers. If it is established that the use of the AFFS, activating sprinklers by means of thermal destruction of a bulb, is ineffective in a given room, the feasibility of forced AFFS activation using a differential heat detector responding to the temperature rise in a room may be considered. The ratios, thus obtained, are applied to identify the acceptable height of premises protected by the AFFS equipped with such detectors. Problem solutions, including the identification of the reason for the ineffective operation of the AFFS, examination of the AFFS in operation, and provision of recommendations to designers, are demonstrated using the exhibition hall as an example.Conclusions. The above-mentioned problems are resolvable with the help of Appendix B to new Construction Regulations 485.13130.2020 and the above models.

Ceiling diffusers are one of the most important elements of ventilation and air-conditioning installations. They have a significant impact on the speed and temperature distribution of air. The basi...

Public buildings such as libraries consume a vast amount of cooling energy for maintaining a comfortable and stable indoor environment in summer, especially in the hot-humid climate. This study used a case study approach to discuss the effect of low-energy strategies that can be applied to improve indoor thermal environment and cooling energy consumption of library buildings in hot and humid cities like Nanning City (a southern city, China). The use of cooling window shutters (a shutter with the effects of shading and evaporative cooling) and ceiling fans for generating airflow was considered as applicable energy-saving measures in this study, and a university library was selected as the study building in which the two energy-saving measures were employed. The SET* and annual cooling load before and after the adoption of the proposed measures were quantitatively investigated with a building energy consumption simulation software (DesignBuilder). Simulation results showed that the daytime SET* values can be reduced by 3.0 °C and 4.5 °C respectively on a typical summer day after the use of the cooling shutters and ceiling fans. Moreover, the cooling loads can also be decreased by 8.4% and 16.6% respectively. Particularly, the combination of these two measures enabled the daytime SET* value and annual cooling load lower by 7.0 °C and 60.8% respectively.

Fences and air curtains can effectively reduce fine dust entry into roadside bus structures, thus decreasing the exposure of passengers to particulate matter. In this study, bus stop structures that reduce the entry of fine dust formed or dispersed by vehicles was derived through simulation models. These bus stop structures consist of a fence that blocks particle entry from a relatively low position in front of the bus stop and an air blast structure that blocks particle entry from a relatively high position. Three bus stop styles were considered: a bus stop without a fence, that with a vertical flat fence, and that with a vertical curved fence toward the road. Among these styles, the curved fence model was superior to other models, and particle entry into the bus stop was estimated to be reduced by 15.5% for the curved fence model compared with the model without a fence. After the selection of the fence model, three air blast structures were considered: canopy, wall, and fence types, which blast air from the ceiling of the bus stop, toward the direction of the road from the rear wall of the bus stop, and upward from the top of the curved fence, respectively. The canopy-type air blast structure was found to be the most effective in decreasing particle entry into bus stops, with a reduction rate of 88% compared with the reference model without a fence and air blast system.

In this paper, we propose a deep learning-based technique for activity detection that uses wide-angle low-resolution infrared (IR) array sensors. Alongside with the main challenge which is how to further improve the performance of IR array sensor-based methods for activity detection, throughout this work, we address the following challenges: we employ a wide-angle infrared array sensor with peripheral vision in comparison to a standard IR array sensor. This makes activities at different positions have different patterns of temperature distribution, making it challenging to learn these different patterns. In addition, unlike previous works, our goal is to perform the activity detection using the least possible amount of information. While the conventional works use a time window equal to 10 seconds where a single event occurs, we aim to identify the activity using a time window of less than 1 second. Nevertheless, we aim to improve over the accuracy obtained in previous work by employing deep learning, while keeping the approach light for it to run on devices with low computational power. Therefore, we use a hybrid deep learning model well suited for the classification of distorted images because the neural network learns the features automatically. In our work, we use two IR sensors ( $32\times24$ pixels), one placed on the wall and one on the ceiling. We collect data simultaneously from both the IR sensors and apply hybrid deep learning classification techniques to classify various activities including “walking”, “standing”, “sitting”, “lying”, “falling”, and the transition between the activities which is referred to as “action change”. This is done in two steps. In the first step, we classify ceiling data and wall data separately as well as the combination of both (ceiling and wall) using a Convolutional Neural Network (CNN). In the second step, the output of the CNN is fed to a Long Short Term Memory (LSTM) with a window size equal to 5 frames to classify the sequence of activities. Through experiments, we show that the classification accuracy of the ceiling data, wall data, and combined data with the LSTM reach 0.96, 0.95, and 0.97, respectively.

A round robin test was carried out in four PV laboratories to compare accelerated lifetime testing. Twenty commercial non-packaged CIGS solar cells of similar performance were spread and exposed to damp heat conditions (85 °C and 85% RH) for approximately 500 h. Their JV performance was monitored during the damp heat exposure. After the test, three of the labs reported average efficiency losses of 87 ± 4%, 89 ± 5% and 92 ± 1%, which are close to median degradation rates found in literature. A higher degradation rate (efficiency loss of 97 ± 3% after only 143 h) was observed in the fourth lab. This was attributed to a poorly designed ceiling window sealing, which caused liquid water pooling on the samples. After modifying the climate chamber, the experiment was repeated with similar samples and an efficiency loss of 72 ± 6% after 475 h was observed for this lab.

In this study, we evaluated the ease of removal of soot layers from ancient wall paintings by employing double network gels as a controllable and safe cleaning method. The ceiling of the temple of Seti I (Abydos, Egypt) is covered with thick layers of soot; this is especially the case in the sanctuary of Osiris. These layers may have been accumulated during the occupation of the temple by Christians, fleeing the Romans in the first centuries A.D. Soot particulates are one of the most common deposits to be removed during conservation-restoration activities of ancient Egyptian wall paintings. They usually mask the painted reliefs and reduce the permeability of the painted surface. A Polyvinyl alcohol-borax/agarose (PVA-B/AG) double network gel was selected for this task since its properties were expected to be compatible with the cleaning treatment requirements. The gel is characterized by its flexibility, permitting to take the shape of the reliefs, while also having self-healing properties, featuring shape stability and an appropriate capacity to retain liquid. The gel was loaded with several cleaning reagents that proved to be effective for soot removal. Soot removal tests were conducted with these gel composites. The cleaned surfaces were evaluated with the naked eye, a digital microscope, and color measurements in order to select the best gel composite. The gel composite, loaded with a solution of 5% ammonia, 0.3% ammonium carbonate, and 0.3% EDTA yielded the most satisfactory results and allowed to safely remove a crust of thick soot layers from the surface. Thus, during the final phase of the study, it was used successfully to clean a larger area of the ceiling.

Due to its significant role in improving indoor air quality, displacement ventilation system is widely adopted in current literature. This paper proposes a displacement ventilation system for room conditions with ceilings that are relatively low, internal heat load could be high, walls could be sunlit, and occupants doing the low physical activity. These conditions are prevalent in the Philippines, being a tropical country. Input parameters to the design process such as heat load, the height of the ceiling, comfort, and indoor air quality requirements were generated, and the main output parameters are the stratification height and ventilation airflow rate. To demonstrate the proposed displacement ventilation system, four cases were generated. Results show that the ventilation airflow rates obtained from the four cases were greater than the minimum outdoor air requirements for health in conference rooms and large assembly areas which are 17.5 and 3.5 liters/sec*person respectively, for smoking and no smoking rooms.

Purpose To evaluate intrafractional head motion (IFM) in patients who underwent intracranial stereotactic radiosurgery with the ExacTrac X-ray system (ETX) and a frameless mask. Methods A total of 143 patients who completed a pre-treatment examination for IFM were eligible for this study. The frameless mask type B R408 (Klarity Medical & Equipment Co., Ltd., Guangzhou, China), which covers the back of the head, and the entire face, was used for patient immobilization. After the initial 6D correction and first X-ray verification (IFM1), X-ray verification was performed every 3 min for a duration of 15 min. The IFMp (2 ≤ p ≤ 6) was calculated as the positional difference from IFM1. In addition, the inter-phase IFM (IP-IFM) and IFMm were calculated. The IP-IFM was defined as |IFMp − IFMp-1|, and IFMm as the difference between the values after all patients were asked to move their heads intentionally with the frameless mask on. Results Both translational IFMp and IP-IFM exceeded 1 mm for a single patient, whereas, for all patients, the translational IFMm values were kept to within 1 mm in all directions. The proportions of the rotational IFMp, IP-IFM, and IFMm values within 0.5° were greater than 94.4%, 98.6%, and 90.2% for all of the rotational axes, respectively. Conclusions A frameless mask achieved highly accurate patient positioning in combination with ETX and a 6°-of-freedom robotic couch; however, a deviation over 1 mm and 0.5° was observed with low frequency. Therefore, X-ray verification and correction are required during treatment.

Assessing the total burden of diseases and other sources of low productivity and premature death in livestock requires a method for capturing the difference between current productivity and a theoretical ceiling within each production system. The animal health loss envelope meets this need.