RESEARCH OF AIR IONIZATION OF AIR IN PREMISES ON OPERATION OF COMPUTER EQUIPMENT

All known studies on the effect of computer equipment on the concentration of air ions of both signs have been used for rooms where desktop computers are operated. The expediency of conducting research using a laptop computer is substantiated. Therefore, the urgent task is to study the dynamics of the air ionic composition of the air from the operation of personal computers and identify ways to maintain this indicator at the regulatory level. It is shown that the switched on computer deionizes air, and mainly on one polarity. It is established that this is a consequence of electrification of polymer surfaces. The cause of electrification is triboelectric phenomena, including the directional movement of dry air from the CPU cooling fan. Additional electrification (and consequently - deionization of air) gives the presence of the user. Confirmation of the cause of deionization is the slow recovery of the concentration of air ions after turning on the computer to a certain neutralization of surface charges. The dependences of the change of air ion concentrations on the distance from the electric field source are established. At its intensity of about 5 kV/m with dimensions of 1.0×1.0 m, the critical distance is 1.2-1.3 m. It is recommended to carry out wet absorption for an unambiguous workplace, which provides insignificant electric fields for 1.5 hours. During the operation of many personal computers, it is advisable to neutralize surface charges with an ultrasonic humidifier-ionizer. It is emphasized that the conducted research has a separate character. This is due to the presence of specific synthetic materials It is advisable to conduct research in standard rooms for the operation of computer equipment to obtain information that can be summarized and used to develop sanitary standards for the operation of computer equipment.

A case of humidifier lung with a difficult differential diagnosis from COVID-19

ABSTRACT Acute respiratory illnesses that presented with diffuse ground-glass opacities (GGOs) on chest computed tomography (CT) scan suggest the diagnosis of coronavirus disease 2019 (COVID-19). However, many other diseases show similar CT findings, which often offer a difficult differential diagnosis. Here, we report a case of humidifier lung, a rare phenotype of hypersensitivity pneumonitis (HP), which mimicked COVID-19. A 71-year-old man was admitted because of dyspnea and diffuse GGOs found on chest CT scan. Although COVID-19 was initially suspected, his symptoms rapidly improved by the next day. A medical interview revealed that he had started using an ultrasonic humidifier 1 month ago. A high-resolution CT (HRCT) scan showed ill-defined centrilobular nodules and mosaic attenuation, which are typical of HP but atypical of COVID-19. The inhalation challenge test confirmed the diagnosis of humidifier lung. History-taking of humidifier use and a precise HRCT interpretation are helpful to differentiate it from COVID-19.

Experimental Investigation of the Effect of a Combination of Active and Passive Cooling Mechanism on the Thermal Characteristics and Efficiency of Solar PV Module

A photovoltaic (PV) module’s electrical efficiency depends on the operating temperature of the cell. Electrical efficiency reduces with increasing PV module temperature which is one of the drawbacks of this technology. This is due to the negative temperature coefficient of a PV module which decreases its voltage significantly while the current increases slightly. This study combines both active and passive cooling mechanisms to improve the electrical output of a PV module. A heat sink made up of aluminum fins and an ultrasonic humidifier were used to cool the panel. The ultrasonic humidifier was used to generate a humid environment at the rear side of the PV module. The cooling process in the study was able to reduce the temperature of the panel averagely by 14.61 ℃. This reduction led to a 6.8% improvement in the electrical efficiency of the module. The average power of 12.23 W was recorded for the cooled panel against 10.87 W for the referenced module. In terms of water consumption, a total of 1.5 L was approximately consumed during the whole experimental process due to evaporation. In effect, the proposed cooling approach was demonstrated as effective.

Development and Evaluation of an Ultrasonic Humidifier to Control Humidity in a Cold Storage Room for Postharvest Quality Management of Dates

Dates are subjected to postharvest losses in quality and quantity caused by water loss, fermentation, insect infestation, and microbial spoilage during storage. Cold storage is the main element in the postharvest quality management used for fruit preservation. Although cold storage is used for dates, precision control of the relative humidity (RH) using ultrasonic applications is not used thus far, or it is applied to other fruits on a small scale. Therefore, we designed and constructed an ultrasonic humidifier (DUH) for RH control in the cold storage room (CSR) of dates. The optimum air velocity of 3 m s−1 at the outlets of the DUH ducts produced a mist amount of 6.8 kg h-1 with an average droplet diameter of 4.26 ± 1.43 µm at the applied voltage of 48 V and frequency of 2600 kHz of the transducers. The experimental validation was carried out by comparing a CSR controlled with the DUH with two conventional CSRs. The three tested CSRs were similar in dimensions, cooling system, and amount of stored dates. The time required for cooling 800 kg of dates in the controlled CSR from 25 °C to the target temperature of 5 °C was approximately 48 h. The DUH precisely controlled the RH at the maximum RH set point of 80% in the tested CSR at 5 °C. The controlled RH at 80% has a positive impact on the physicochemical characteristics of the stored dates. It significantly reduced the weight loss of the fruits and preserved fruit mass, moisture content, water activity, firmness, and color parameters. However, no significant effect was observed on fruit dimensions, sphericity, and aspect ratio. The microbial loads of mesophilic aerobic bacteria, molds, and yeasts fell within the acceptable limits in all tested CSRs. Both stored date fruits and artificially infested dates showed no signs of insect activity in the controlled CSR at the temperature of 5 °C and RH of 80%. The DUH proved to be a promising technology for postharvest quality management for dates during cold storage.

Combining Indoor Positioning Using Wi-Fi Round-trip Time with Dust Measurement in the Field of Occupational Health

[Objectives] The measurement of personal exposure has been attracting increased attention for the control of hazardous substances. Although the combination of location information and personal exposure is considered highly useful, to-this-date, no simple or highly accurate indoor positioning method has been presented. Recently, Wi-Fi round-trip time (RTT) has attracted scientific attention as a highly accurate indoor positioning method. In this study, we investigated the possibility of the use of a combination of this indoor positioning method and small-dust sensors. [Methods] We measured indoor positioning and dust concentration three times during a walk in a simulated factory. A wearable particle monitor was worn on both upper arms, and a smartphone was attached to the helmet for positioning. An ultrasonic humidifier was used to spray sodium chloride solution in the factory. The measurements were conducted three times on different routes on foot (Experiment A, B, C). [Results] In indoor positioning, the error percentages, i.e., measurements that were outside the correct measurement area were 7% (49 s/700 s) in Experiment A, 2.3% (15 s/660 s) in Experiment B, and 7.8% (50 s/645 s) in Experiment C . The dust measurements were also taken without interruption. A heat map was created based on the results of both measurements. [Conclusions] Wi-Fi RTT was able to implement indoor positioning with high accuracy. Thus, the combination of indoor positioning and various sensors can be considered useful for occupational health.