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Heat recovery ventilation (HRV) system is emerging as a sustainable technology to reduce human exposure to air pollutants in residential buildings. However, there is a lack of information on the HRV system performance for controlling both indoor-generated and outdoor-generated particles in a residential building. To fill this knowledge gap, we conducted field monitoring of indoor airborne particles with two representative HRV system operating modes (ventilation and circulation modes) in a full-scale residential testbed. The results reveal that the filter efficiency, airflow rate, and filter bypass factor of the HRV system play important roles in indoor particle concentrations. The indoor/outdoor concentration ratio is reduced by 72%–92% when operating the HRV system. For both circulation and ventilation modes, the bypass factor is crucial for the particle removal performance of the HRV system. A 20% filter bypass factor leads to up to a 50% increase in indoor exposure to outdoor-originated and indoor-generated PM 2.5 compared to the no-bypass scenario. Although circulation mode performed better than ventilation mode, both operating modes with a minimal bypass factor can effectively remove particles generated from indoor emission sources (e.g., incense stick burning and bacon pan frying). The study results suggest that HRV system can reduce human exposure to indoor-generated particles by 56%–90% and particle control performance hinges upon minimizing HRV filter bypass. • We investigate indoor particle removal due to a heat recovery ventilation system. • The HRV system can reduce human exposure to indoor-generated particles by 50–90%. • The filter bypass factor is crucial for the HRV particle control performance. • A 20% filter bypass factor can lead up to 50% increase in indoor PM2.5 exposure. [ABSTRACT FROM AUTHOR]

• Propose the optimal ventilation strategy to reduce particle exposure in a hospital ward by comparing various air distribution patterns and different ward patterns. • Measure the temperature field, airflow velocity field and concentration field of particulate matter in different air distribution forms accurately and establish a large number of databases. • Assess the infection risk duo to inhalation exposure of the healthcare worker and patients to viral particles released by the patient in the same ward on different air distribution forms. In recent years, a large number of respiratory infectious diseases (especially COVID-19) have broken out worldwide. Respiratory infectious viruses may be released in the air, resulting in cross-infection between patients and medical workers. Indoor ventilation systems can be adjusted to affect fine particles containing viruses. This study was aimed at performing a series of experiments to evaluate the ventilation performance and assess the exposure of healthcare workers (HW) to virus-laden particles released by patients in a confined experimental chamber. In a typical ward setting, four categories (top supply and exhaust, side supply and exhaust) were evaluated, encompassing 16 different air distribution patterns. The maximum reduction in the cumulative exposure level for HW was 70.8% in ventilation strategy D (upper diffusers on the sidewall supply and lower diffusers on the same sidewall return). The minimum value of the cumulative exposure level for a patient close to the source of the contamination pertained to Strategy E (upper diffusers on the sidewall supply and lower diffusers on the opposite sidewall return). Lateral ventilation strategies can provide significant guidance for ward operation to minimizing the airborne virus contamination. This study can provide a reference for sustainable buildings to construct a healthy indoor environment. [ABSTRACT FROM AUTHOR]

The color image processing based on the color information is not concerned with the accuracy of the color information in the original image. The color representation transformation and the processing algorithm assume that the accuracy of the input image is sufficiently high. This paper considers the input of the RGB color image, and discusses the image input system, emphasizing the accuracy of the color information. Here, each pixel is inputted with sufficient intensity without saturation, independently of the brightness of the object, by the multistep exposure control. The obtained image is called the adaptive exposure color image since each pixel is inputted with an adequate exposure. This paper discusses also the exposure control using the variable electronic shutter function of the CCD camera, the pixel selection/storage algorithm for the time-series images with different exposure times, and the reduction of the input time by reducing the number of exposures. By an input experiment, it is verified that a stable input of the color image is realized for the scene with a high contrast, containing multiple colors and shadows. The region segmentation based on the chromatic component is considered, and it is shown that the adaptive exposure color image realizes satisfactory colors over the whole image compared to the ordinary color image. Thus the method is shown to be useful in improving the accuracy from the viewpoint of color discrimination and other applications. [ABSTRACT FROM AUTHOR]