Proposing a new tracer gas for future field applications of passive tracer gas tests for air change rate measurement

This paper describes the ongoing development of a new adaptation of the traditional tracer gas test (TGT) used for total air change rates (ACH) measurement. This adapted TGT, based on constant tracer injection, is intended for use in large-scale IAQ assessments and employs an alternative tracer gas that is more adequate than the currently employed SF6 and perfluorocarbons, and that can be co-captured and coanalysed with commonly assessed VOCs by commercial passive IAQ-sampling. Via literature study and lab experiments, decane-D22 was found to be a suitable tracer substance. A passive source of decane- D22 was developed and optimized in lab, providing stable and repeatable emission rates under standard temperature, while unaffected by varying RH and ACH. The effect of the liquid solvent level over the source emission rate was only barely noticeable, but a range of adequate solvent level is suggested nevertheless. The selected tracer was also shown not to adhere/absorb significantly to surfaces. Additionally, a consistent exponential curve was derived for determining the source emission rate from the room temperature. Field applications of this new TGT adaptation are ongoing and will be published elsewhere shortly.publishedVersio

Work with motivated and gifted students in physics in RCT “Mihajlo Pupin” from Pančevo - a review of the last 15 years

Since the very beginning, Regional Center for Talents “Mihajlo Pupin” in Pančevo had a physics group. Over time, the number of classes has grown, but so did the number of students and mentors. Consequently, the achievements on national and even international competitions in physics were growing steadily. After first few years spent in experimenting different possibilities in the field of work with talented students in physics, the standard of classes has been established. Such standard, with the help of motivated students and mentors has produced a successful mechanism for preparing students for various challenges in the field of physics and beyond. This paper presents a model of working in the physics group in Regional Center for Talents “Mihajlo Pupin” in Pančevo, as well as the results our students have achieved on national and international physics and science competitions in the last 15 years of work.BPU11 : 11th International Conference of the Balkan Physical Union : Proceedings book; Aug 11 - Sep 1, 2022S14-PEHPP Physics Education, History and Philosophy of Physic

To touch or not to touch : A comparison between traditional and touchscreen interface within personal computers

Touchscreen technology is gradually becoming more popular and massive in our present society to the point where it is hard to find a person that has never used this interface system. Handheld devices such as mobile phones and tablets are predominantly based on touchscreens as the main way to interact with them. Nevertheless, that is not the case when it comes to personal computers either desktop machines or laptops which are still chiefly based on traditional keyboard and mouse as their main input system. In this study we explore the potential that touchscreen based interface can offer for personal computers carrying through an observational experiment with six participants that were asked to perform a list of tasks using both traditional keyboard-mouse interface and touchscreen interface. The measurements during the observation concerned time and error rate for every task. Each participant was interviewed right after the completion of the observational phase in order to get a qualitative insight on their views and perceptions regarding both interfaces. The data collected was analyzed based on some existing models within touchscreen interface and human-computer interaction that have been elaborated in previews research. The final results led to the conclusion, that touchscreen-based interface proved to be slower and have higher error rate than traditional interface in a big number of the tasks performed by the participants. Similarly, the general perception of the people towards having touchscreen on a personal computer still seems a bit doubtful, although they do see some concrete positive aspects about this interface. Nevertheless, touchscreen outperformed traditional interface in some particular tasks. This implies that touchscreen interface has a clear potential for personal computers that would let users utilize these machines in a much broader and more interactive way than people do it today with the traditional keyboard-mouse interface.

Mass transfer of an organophosphate flame retardant between product source and dust in direct contact

Organophosphate flame retardants (OPFRs) are a group of semi-volatile organic compounds (SVOCs) and among the most abundant contaminants indoors. Their indoor presence has been associated with potential health risks however there is limited understanding as to how they are released from indoor sources. This study uses an emission micro-chamber to explore one of the currently understudied chemical migration pathways; direct transfer between a source material and settled dust in contact with the source. A tris(2-chloroisopropyl) phosphate (TCIPP)-treated insulation board is used as the source material. Rapid and substantial transfer was observed after only 8 h of source-dust contact, resulting in 80 times higher concentrations in dust compared to pre-experiment levels. Further time points at 24 h and 7 d showed similarly high average dust levels and the TCIPP in the dust and air in the chamber was calculated to be close to thermodynamic equilibrium. It was concluded that TCIPP was effectively transferred from the insulation board to the dust on its surface and the surrounding air via gas-phase diffusion. In a real room, a gradient of TCIPP concentrations in air above the surface of a product could result in higher concentrations in dust sitting on the product than dust in the rest of the room

Reliability of lower-cost sensors in the analysis of indoor air quality on board ships

Air quality in and around ships is governed by a variety of pollution sources that are unique for the shipping context. This makes the living and working conditions on ships substantially different from situations in cities or inside buildings. To gain insight into these differences, information about trends and absolute pollutant amounts on board ships is needed. However, the installation of reference instruments to monitor NO2, NO, O3, particulate matter and other environmental parameters is often not possible because of their size, weight or because of safety reasons. For that reason, more compact devices incorporating a variety of sensors are a good alternative. However, the use of such sensors is only possible when their behaviour and performance in a shipping context are well understood. To study this context, we were allowed to compare sensor-based measurements performed on a 36-year old ship dedicated to near shore operations with measurements of reference-grade instruments. Additional behavioural information of sensors is obtained by measuring campaigns organized on several inland ships. This contribution demonstrates that trends registered by gas and particulate matter sensors are reliable but that insufficient detection limits, higher noise, imperfect calibration and sensor errors result in some reliability constraints

Proposing a new tracer gas for future field applications of passive tracer gas tests for air change rate measurement

This paper describes the ongoing development of a new adaptation of the traditional tracer gas test (TGT) used for total air change rates (ACH) measurement. This adapted TGT, based on constant tracer injection, is intended for use in large-scale IAQ assessments and employs an alternative tracer gas that is more adequate than the currently employed SF6 and perfluorocarbons, and that can be co-captured and coanalysed with commonly assessed VOCs by commercial passive IAQ-sampling. Via literature study and lab experiments, decane-D22 was found to be a suitable tracer substance. A passive source of decane- D22 was developed and optimized in lab, providing stable and repeatable emission rates under standard temperature, while unaffected by varying RH and ACH. The effect of the liquid solvent level over the source emission rate was only barely noticeable, but a range of adequate solvent level is suggested nevertheless. The selected tracer was also shown not to adhere/absorb significantly to surfaces. Additionally, a consistent exponential curve was derived for determining the source emission rate from the room temperature. Field applications of this new TGT adaptation are ongoing and will be published elsewhere shortly

Application of adapted tracer gas test for ventilation assessment in two locations

In the wake of the current worldwide COVID crisis, the vital role of ventilation in keeping healthy indoor environments has become increasingly clear. But even before that, researchers have been pointing out how crucial ventilation is in avoiding the accumulation of pollutants in indoor spaces and in interpreting indoor air quality (IAQ) data. Given the importance of ventilation, especially in estimating pollutant sources’ strength and proposing remediation actions, it is imperative that IAQ assessments quantify the actual building ventilation rates. However, many IAQ field studies found in the literature do not report ventilation rates adequately. This paper describes the application of an alternative method to passively measure the average ventilation in two different locations. This alternative method consists of an adaptation of the traditional tracer gas test (TGT) used for long term average air change rates (ACH) measurement. This adapted TGT employs an alternative tracer gas (decane-D22) that is more adequate than the currently employed SF6 and perfluorocarbons. The selected tracer can be co-captured and co-analysed with commonly assessed VOCs by commercial passive IAQ-sampling. A passive source design of decane-D22, optimized in lab, provides stable and repeatable emission rates unaffected by varying RH and ACH. The actual source emission rate is determined from the average room temperature via an exponential prediction curve derived in lab. Results from the two field experiments described in this paper show the satisfactory applicability of the proposed adapted TGT in different types of environments and settings. The ultimate research goal is to provide an accessible enough method to quantify ventilation that it may encourage researchers, contractors and building owners to perform appropriate ventilation assessments more often and with a good degree of accurateness