Maximum Exposure Time Research Articles

Cybersickness in People with Multiple Sclerosis Exposed to Immersive Virtual Reality.

Together with the wide range of possible benefits for the rehabilitation/training of people with multiple sclerosis (pwMS) and other neurologic conditions, exposure to immersive virtual reality (VR) has often been associated with unpleasant symptoms, such as transient dizziness, headache, nausea, disorientation and impaired postural control (i.e., cybersickness). Since these symptoms can significantly impact the safety and tolerability of the treatment, it appears important to correctly estimate their presence and magnitude. Given the existing data scarcity, this study aims to assess the existence and severity of possible adverse effects associated with exposure to immersive VR in a cohort of pwMS using both objective measurements of postural control effectiveness and subjective evaluations of perceived symptoms. To this aim, postural sway under upright quiet posture (in the presence and absence of visual input) of 56 pwMS with an Expanded Disability Status Scale score (EDSS) in the range of 0-6.5 (mean EDSS 2.3) and 33 unaffected individuals was measured before and after a 10-min immersive VR session and at 10 min follow-up on the basis of center of pressure (COP) trajectories. The severity of cybersickness symptoms associated with VR exposure was also self-rated by the participants using the Italian version of the Simulator Sickness Questionnaire (SSQ). Temporary impairments of postural control in terms of significantly increased sway area were observed after the VR session only in pwMS with mild-moderate disability (i.e., EDSS in the range of 2.5-6.5) in the presence of visual input. No changes were observed in pwMS with low disability (EDSS 0-2) and unaffected individuals. In contrast, when the visual input was removed, there was a decrease in sway area (pwMS with mild-moderate disability) and COP path length relating to the use of VR (pwMS with mild-moderate disability and unaffected individuals), thus suggesting a sort of "balance training effect". Even in this case, the baseline values were restored at follow-up. All participants, regardless of their status, experienced significant post-VR side effects, especially in terms of blurred vision and nausea. Taken together, the findings of the present study suggest that a short immersive VR session negatively (eyes open) and positively (eyes closed) impacts the postural control of pwMS and causes significant disorientation. However, such effects are of limited duration. While it is reasonable to state that immersive VR is sufficiently safe and tolerable to not be contraindicated in the rehabilitation/training of pwMS, in order to reduce possible negative effects and maximize the efficacy, safety and comfort of the treatment, it appears necessary to develop specific guidelines that consider important factors like individual susceptibility, maximum exposure time according to the specific features of the simulation, posture to adopt and protocols to assess objective and perceived effects on participants.

Natural products as a control measure of the Achatina fulica (Gastropoda: Achatinidae).

Achatina fulica is a terrestrial mollusk known as the giant African snail that is related to environmental, economic, urban, and public health problems. As control measures for this mollusk, cooking salt (NaCl) and calcium oxide (CaO) are used, and baits are composed of metaldehyde. However, these measures have environmental toxicity and impact the soil. In this way, natural products have been tested on this mollusk to discover and develop a substance to combat this urban and agricultural pest. This article aims to evaluate studies involving natural products to control the population of Achatina fulica. Articles and works published in books were included in the present work. A total of 1,103 works were found during the search. Of these, 14 works met the objective of these review and were included in this article. The tests do not possess methodological standardization, do not have a maximum concentration to be considered active, or a maximum exposure time. A lack of standardization in the methodology of tests on A. fulica was observed. The performance of tests on other life stages of the mollusk, as well as tests that analyze other parameters, are essential. Only one article analyzed presented phytochemical analysis. No ecotoxicity tests were reported either. Some extracts showed promising results, highlighting the aqueous extract of Capsicum frutescens. More studies investigating the molluscicidal activity of natural products on A. fulica are needed. It is very relevant that the new studies present a phytochemical analysis of the tested extracts, as well as ecotoxicity studies.

Analisis Tingkat Kebisingan pada Workshop Alsintan UPTD Balai Benih Induk Tanaman Pangan dan Alsintan Provinsi Lampung

Activities in agricultural machinery workshops must concern with Occupational Health and Safety (OHS), especially the physical conditions of the work environment. There are potential physical dangers, especially noise from machines in the workshop. This research aims to analyze the noise level at the UPTD Agricultural Machinery Workshop, Main Center for Food Crops and Agricultural Machinery, Lampung Province, and provides recommendations for control engineering. The parameters observed in the research were noise, temperature and humidity. Noise level was measured by using a sound level meter for the source of the sound when the machines were turned on, at fifty measurement points determined based on applicable regulations. Temperature and humidity were measured using a digital hygrometer thermometer, at three observation points. The measurement results were compared with the applied quality standards in Indonesia. Noise measurement resulted (88.29 ± 11.58) dBA, with 7 sound sources turned on simultaneously. Based on Minister of Manpower Regulation No. 5 of 2018, at this noise level the maximum exposure time for workers is 4 hours per day. If the time limit exceeds, workers must use ear protection or do the job in rotation (in shift work). Average temperature measurement resulted (28.8 ± 0.3)°C and average humidity measurement (61.5 ± 7.8)%. Referring to the Decree of the Minister of Health of the Republic of Indonesia No. 1405 of 2002, the air temperature and humidity at the UPTD Agricultural Machinery Workshop, Main Center for Food Crops and Agricultural Machinery, Lampung Province is still above the requirements for working environmental health. Keywords: Ergonomics, Noise, OHS, Physical Environment, Potential Physical Hazards.

Corrosion behavior of iron-based and Ni-based alloys melted in NaCl–MgCl2–KCl mixed molten salt under vacuum atmosphere

In this work, static immersion and gravimetric methods were used to study the corrosion behavior of three common stainless steels and four Ni-based alloys in a NaCl–MgCl2–KCl mixed molten salt under vacuum atmosphere. The corrosion test was conducted at 700 °C, with a maximum exposure time of 100 h. Corrosion behavior was determined by measuring the mass loss of the sample at different time intervals and the corrosion rates at 100 h. The microstructure of the alloy was analyzed by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), atomic force microscope (AFM), and X-ray diffraction (XRD). The results showed that stainless steels were generally more severely corroded than Ni-based alloys. 304 stainless steel and In800H exhibited the worst corrosion resistance, whereas Ni-based alloy In625 had the best corrosion resistance. Fe and Cr were dissolved in the molten chloride salts and reacted with the molten chloride salts. Mo played a positive role in suppressing the corrosion of the alloys in molten chloride salts by inhibiting the outward diffusion of the elements.

Study on the mechanical properties of Self-Curing Concrete Using Magnetized Water

The growth of the population has led to an increase in construction activities, which require water for concrete mixing, curing, and cement hydration. Cement hydration occurs due to extra water that is not part of the mixing water. Magnetized water, which is water subjected to magnetic flux, has become a popular technology in the construction industry due to its potential to increase the lifespan of buildings and improve various technological processes at an economical cost. The use of magnetically processed water reduces the amount of cement needed to achieve the desired compressive strength value. This study investigates the effects of magnetic field generated by Permag N-406 on the properties of water, such as pH and hardness also, cement is partially replaced with 1%-4% of Nano Silica to achieve good characteristic strength. The study determines the optimal magnetization value, the maximum exposure time of water to the magnetic field and, the mechanical properties of self-curing concrete. Polyethylene Glycol (PEG) is used as the self-curing agent. The experiment results shows that the 48 hrs of magnetization of water and replacement of cement by 3% of Nano Silica showed the better performances in mechanical properties.

Camera Attributes Control for Visual Odometry With Motion Blur Awareness

The practical application of visual odometry (VO) is challenging under High Dynamic Range (HDR) environments which has a significant impact on the quality of feature point tracking. There are two key attributes that affect the image quality of a camera, namely exposure time and gain. The goal of camera attributes control research is to design algorithms that can actively adjust camera acquisition attributes to obtain clear, information-rich images. We propose an efficient and stable camera attributes control method with distinct image quality metrics and a linear convergence search algorithm. Specifically, we propose to use the weighted sum of image gradient and entropy to represent the image quality. Its first order derivative is also computed for a line search algorithm to determine the optimal camera exposure. Then, the algorithm estimates scene change speed by optical flow and finds out the maximum exposure time without motion blur. Ultimately, the maximum exposure time and optimal camera exposure are used to determine the camera properties including exposure time and gain. Additionally, the proposed method speeds up the convergence of the algorithm with the help of simulated image generation which enables nearly optimal attributes to be obtained directly from an overexposed or underexposed image. To validate the proposed approach, we test it in challenging HDR environments with fast motion and compare it with built-in automatic exposure. It will be open source for the benefit of the community.

Report on Existing Fireproof Construction Guidelines for Dwellings against Wildfires

This work presents a state-of-the-art review of existing fireproof construction guidelines for dwellings against wildfires. The most important wildfire-proof construction guidelines and codes for dwellings are presented, and these are later associated with existing fire engineering chapters associated with building codes. It was concluded that the variability in this subject is very high, and the approach to classifying the thermal effects in construction still lags behind scientific consensus. Moreover, the constructive requirements depend severally on the country’s building code when assessing the fireproof requirements for wildfire. Moreover, the thermal actions of wildfires in dwellings are presented and compared with classical ISO-834 standard fire curves, in which the maximum equivalent fire exposure time can range from 2 to 4 h depending on the country’s code. The key contributions of this work consist of (i) thoroughly disseminating codes and guidelines to promote scientific discussion in order to advance the wildfire fireproof standards dedicated to WUI; (ii) emphasizing the void in current codes in order to promote conversation between future researchers.

Chloride penetration resistance of engineered cementitious composite (ECC) subjected to sustained flexural loading

This paper presents a research on the chloride penetration behavior of engineered cementitious composites (ECC) under sustained flexural loads. Three load levels, i.e. 30 %, 60 % and 75 % of the ultimate flexural load were used. Chloride diffusion depth and concentration profile were measured 30, 60 and 150 days after the specimen was exposed to NaCl solution and compared with pre-loaded specimens. Influence of the sustained local bending stress and microcracks were investigated. It shows that under sustained loads, the relationship between the surface chloride content and maximum normal tensile stress can be described using an exponential equation. A binary model was developed to explain the correlation among the chloride ion diffusion coefficient, maximum normal tensile stress and exposure time. Changes of capillary pore structure and phase compositions were measured using mercury intrusion porosimeter and X-ray diffraction, respectively. Unlike mortar, the fiber bridging of ECC helps with limiting crack width and thus the diffusion process, and the measured results were used to explain the observed penetration behavior of ECC. It is believed that the current study provides theoretical foundation for the durable design of the ECC/concrete composite structure.

Analysis of image motion for optical remote sensing satellites staring imaging with area-array detectors.

In this paper, the image motion introduced by the staring action itself during optical remote sensing satellites staring imaging with area-array detectors is studied. The image motion is decomposed into the angle-rotation image motion caused by the change of observation angle, the size-scaling image motion caused by the change of observation distance, and the Earth-rotation image motion caused by the rotation of the ground object with the Earth. The theoretical derivation of the angle-rotation image motion and size-scaling image motion is conducted, and the numerical analysis of the Earth-rotation image motion is carried out. Based on the comparison among the characteristics of the three types of image motions, the conclusion is drawn that, for general staring imaging scenes, the angle-rotation image motion is dominant, followed by the size-scaling image motion and the ignorable Earth-rotation image motion. On the condition that the image motion does not exceed 1 pixel, the allowed maximum exposure time for area-array staring imaging is analyzed. It is found that the large-array satellite is not suitable for long-exposure imaging, as its allowed exposure time decreases rapidly with the increase of roll angle. A satellite with a 12k×12k area-array detector and 500km orbit is taken as an example. The allowed exposure time is 0.88s when roll angle of the satellite is 0°; it decreases to 0.02s when the roll angle increases to 28°.

Design of an optimised movable electrostatic diagnostic for the investigation of plasma properties in a large negative ion source

This contribution describes the design of a movable Langmuir probe system to be permanently installed in the SPIDER negative ion source. This diagnostic aims at measuring the axial profiles of plasma density, electron temperature and floating potential in both the driver and the expansion region, with a view to further investigate the positive ion dynamics. Furthermore, a deeper understanding of the plasma formation mechanism and of the RF coupling can be provided, e,g. via the estimation of the Electron Energy Distribution Function (EEDF) inside the driver. Thermal analyses were performed to define both the allowable duration of the probe exposure to the plasma and the extent of the voltage sweep. The maximum exposure time for the probe shaft is 10 s, thus a fast manipulation system is included in the design. The integration in the SPIDER source is described, considering all the limitations due to the space availability, the presence of the RF generators and the vacuum-compatibility requirements. To comply with all the constraints, several solutions are proposed for the probe head design.

Efficiency of Paecilomyces variotii in Bioremoval of Reactive Black Dye from Tannery Effluent

The present work investigates the efficiency of Paecilomyces variotii upon degrading Reactive Black dye which has been termed a recalcitrant variety of synthetic dye. In this research, initially a predominant fungal species, Paecilomyces variotii was isolated from the tannery effluent sample. The study was carried out by assessing the ability of fungi to decolorize the dye under various parameters like pH (5,7 and 9), Temperature (7°C, 30°C, and 45°C), Dye concentration (200, 300, and 400 mg/L) for different incubation or exposure time interval (3, 5 and 7 days). From the experimental study, it was found that Paecilomyces variotii showed a maximum percentage of dye decolorization at 7°C at pH 9 with 75%, at 30°C at pH 7 with 85%, at 45°C at pH 5 with 82% and a maximum period of incubation with 7 days in 200 mg.L-1 concentration. This result conveys that the strength of Paecilomyces variotii in decolorizing the synthetic dye is effective at a moderate temperature with neutral pH for maximum exposure time. So Paecilomyces variotii could be a good candidate of choice for the biodegradation of various synthetic dyes when manipulated wisely. Also, the result sparks a positive attribute toward decreasing industrial wastewater pollution.

Raman spectroscopic evaluation of precision of oxygen isotope ratio of carbon dioxide

We measured the Raman spectra of CO2 fluid at 30 MPa and room temperature (19.1–21.3°C). The spectra showed peaks attributed to the CO2 combining various isotopes such as 12C16O2, 13C16O2, and 12C16O18O. The relative ratio of 12C16O2 to 12C16O18O peaks represents the oxygen isotope ratio of CO2. To evaluate the precision of the peak ratios, we measured the CO2 Raman spectra at different exposure times. We examined the standard deviation (1 σ) of the peak intensity ratios and area ones for 20 measurements at each exposure time. The standard deviations of the intensity ratios and area ones were 2.7 and 3.1%, respectively, at a maximum exposure time of 494 s, conversion to peak intensity of 12C16O2 yields about 2,000,000 counts. The uncertainties are 2.5–3 times greater than expected from the noise of a CCD camera and photon statistics. The oxygen isotope ratios (δ18O) of natural samples have a range of variation of about 16.6%. Compared to that value, the precision we obtained from this study is very small. Raman spectroscopy can be combined with microscopy to analyze areas as small as approx. 1 µm in diameter. Therefore, oxygen isotope measurement using Raman spectroscopy has potential for application to natural samples as a new method for small CO2 fluids such as fluid inclusions.

Synthesis of nanocomposites reduced graphene oxide-silver nanoparticles prepared by hydrothermal technique using sodium borohydride as a reductor for photocatalytic degradation of Pb ions in aqueous solution

Heavy metals are pollutants that are harmful to living things and the environment can be degraded by microbes or understood by other living things so that they can cause health problems. One of the heavy metals that is often found in wastewater is lead. Lead is widely used in the manufacture of batteries, metal products such as ammunition, cable coatings, Polyvinyl Chloride (PVC) tubing, solder, chemicals and dyes This use causes humans to be exposed to large amounts of lead. One method to deal with lead pollution is to use photocatalysts. Photocatalysts react with heavy metals and reduce them so that the level of toxicity becomes lower than before through photocatalytic reactions. In this study, synthesis of reduced graphene oxide/silver nanoparticle nanoparticles was performed by facile hydrothermal methods for photocatalytic degradation of Pb ion. The characterization results indicate that the synthesis has been successfully carried out. The successful result of rGO/AgNPs nanocomposites synthesis was proved by several techniques such as X-ray diffraction analysis, Raman, UV-Vis spectroscopy, Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray analysis (EDX). This indicates the presence of these groups in the graphene oxide and rGO/AgNPs samples, respectively. The resulting rGO/AgNPs nanocomposite has an absorbance peak at a wavelength of 267 nm. The diffraction peaks for nanocomposites rGO/AgNPs and their Miller indices were 38.08° (111), 44.16° (200), 64.44° (220), and 77.44° (311). The Raman spectra of rGO/AgNPs exhibits D bands at 1334,13 with intensity of 630,60 cm−1 and G band at 1594,61 with intensity of 477,29 cm−1. The ID/IG ratio rGO/AgNPs-NaBH4 is ~1,32. Furthermore, the photocatalytic activity test results showed that the rGO/AgNPs nanocomposite was able to reduce Pb2+ to Pb with a maximum exposure time of 1.5 hours

Epidemiology and Determinants of Vitamin D Deficiency in Eastern Nepal: A Community-Based, Cross-Sectional Study.

Objective To estimate the prevalence of vitamin D deficiency in the eastern part of Nepal and identify the sociodemographic factors associated with it. Methods A descriptive cross-sectional study was carried out among 324 participants between the ages 18 and 65 years from the Sunsari and Morang districts of Nepal. A semi-structured questionnaire helped obtain sociodemographic data followed by anthropometric measurements and blood sampling. 25(OH)D level was measured by chemiluminescence immunoassay (CLIA) via a fully automated Maglumi 1000 analyzer (SNIBE Co., Ltd., China). Serum 25(OH)D was classified as deficient, insufficient, and sufficient (<20 ng/ml, 20–29 ng/ml, and 30–100 ng/ml, respectively). The chi-square test was used to analyze the sociodemographic variables followed by a post hoc analysis. Significant variables were subjected to multivariate logistic regression. Result 181(55.9%) of the study population had vitamin D deficiency. There was significant association between vitamin D status and time of maximum sun exposure (chi square test = 11.1, p = 0.02), duration of sun exposure (chi-square test = 15.1, p = 0.004), type of meat intake (Fisher's exact test is 16.4, p = 0.01), frequency of fish intake (Fisher's exact test is 19.3, p = 0.001), and frequency of dairy intake (chi-square test=11.2, p = 0.02). In multivariate regression, consumption of dairy products ≥3/week had lower OR (95% CI) (0.3(0.1–0.8) p : 0.02) and weekly fish consumption had lower OR (95% CI) (0.06(0.008–0.6) p : 0.01) for vitamin D deficiency. Conclusion The prevalence of vitamin D deficiency was relatively high in eastern Nepal. This highlights the need to create public awareness regarding the importance of bare skin sun exposure, nutritional sources of vitamin D, and the need to implement food fortification policies by the government.

A comparison of activity data generated from cardiovascular telemetry studies - With quantitative open field locomotor studies in Wistar Han rats

Compound-mediated locomotion changes, conducted via open field infrared photobeam breaks, are an important common component of neurological assessments conducted in safety pharmacology studies. In addition to open field locomotor activity assessments, activity data (derived from changes in signal strength) from cardiovascular (CV) telemetry studies can also be an alternative method potentially used to assess locomotor effects. However, comparisons of these two methods have not been extensively characterized. The goal of this work was to compare these two methodologies to assess activity in rats using reference compounds known to have central nervous system (CNS)-stimulant (preladenant) or CNS-depressant (chlorpromazine) effects. Open field activity was conducted using the Kinder Scientific Motor Monitor system and data were collected for 30 min at each drug's expected time of maximum plasma exposure (Tmax). Telemetry-based CV assessment data were continuously acquired using DSI radiotelemetry instrumented animals for 24 h postdose (HPD). Drugs were administered during the lights-on period for both study types. Administration of preladenant caused increases in activity within 0.5–2 HPD for both methods. While administration of chlorpromazine caused decreases in activity in the infrared beam-based open field assessment (1.0–1.5 HPD), there was no effect on telemetry-derived activity during a similar time period. However, telemetry-derived decreases in activity were observed during the lights-off period (16–20 HPD), suggesting CNS-depressant compounds may be mischaracterized if the optimal dose administration time is not selected based on the light/dark cycle and pharmacokinetics. Overall, these results suggest that telemetry-based activity assessment is capable of detecting CNS-stimulant effects of compounds.

The potential ‘blue light hazard’ from LED headlamps

Many dental personnel use light-emitting diode (LED) headlamps for hours every day. The potential retinal ‘blue light hazard’ from these white light headlamps is unknown. MethodsThe spectral radiant powers received from direct and indirect viewing of an electronic tablet, an LED curing light, a halogen headlamp, and 6 brands of LED headlamps were measured using integrating spheres attached to fiberoptic spectroradiometers. The spectral radiant powers were measured both directly and indirectly at a 35 cm distance, and the maximum daily exposure times (tMAX) were calculated from the blue weighted irradiance values. ResultsThe headlamps emitted very different radiant powers, emission spectra, and color temperatures (K). The total powers emitted at zero distance ranged from 47 mW from the halogen headlamp to 378 mW from the most powerful LED headlamp. The color temperatures from the headlamps ranged from 3098 K to 7253 K. The tMAX exposure times in an 8 h day when the headlamps were viewed directly at a distance of 35 cm were: 810 s from the halogen headlamp, 53 to 220 s from the LED headlamps, and 62 s from the LED curing light. Light from the LED headlamps that was reflected back from a white reference tile 35 cm away did not exceed the maximum permissible exposure time for healthy adults. Using a blue dental dam increased the amount of reflected blue light, but tMAX was still greater than 24 h. ConclusionsWhite light LED headlamps emit very different spectra, and they all increase the retinal ‘blue light hazard’ compared to a halogen source. When the headlamps were viewed directly at a distance of 35 cm, the ‘blue light hazard’ from some headlamps was greater than from the LED curing light (tMAX = 62 s). Depending on the headlamp brand, tMAX could be reached after only 53s. The light from the LED headlamps that was reflected back from a white surface that was 35 cm away did not exceed the maximum permissible ocular exposure limits for healthy adults. Clinical relevanceReflected white light from dental headlamps does not pose a blue light hazard for healthy adults. Direct viewing may be hazardous, but the hazard can be prevented by using the appropriate blue-light blocking glasses.

Viability of Wildflower Seeds After Mesophilic Anaerobic Digestion in Lab-Scale Biogas Reactors.

The use of wildflower species as biogas feedstock carries the risk that their seeds survive anaerobic digestion (AD) and cause weed problems if spread with the digestate. Risk factors for seed survival in AD include low temperature, short exposure and hardseededness (HS). However, it is not possible to predict how AD will affect seed viability of previously unstudied species. In laboratory-scale reactors, we exposed seeds of eight species from a mixture of flowering wild plants intended as biogas feedstock and three reference species to AD at two mesophilic temperatures. Half of the species were HS, the other was non-HS (NHS). Viability was determined using a combination of tetrazolium and germination tests. Viability and germinability were modeled as functions of exposure time using a dose-response approach. Responses to AD varied considerably among species, and none of the considered influencing factors (time, temperature, HS) had a consistent effect. Seed lots of a species differed in inactivation times and seed-killing efficacy. The HS species Melilotus officinalis, Melilotus albus, and Malva sylvestris were particularly AD-resistant. They were the only ones that exhibited biphasic viability curves and tended to survive and germinate more at 42°C than at 35°C. Viability of the remaining species declined in a sigmoidal curve. Most NHS species were inactivated within a few days (Cichorium intybus, Daucus carota, Echium vulgare, and Verbascum thapsus), while HS species survived longer (Malva alcea). AD stimulated germination in the HS species A. theophrasti and its AD-resistance overlapped with that of the most resistant NHS species, C. album and tomato. In all seed lots, germinability was lost faster than viability, implying that mainly dormant seeds survived. After the maximum exposure time of 36 days, seeds of HS species and Chenopodium album were still viable. We concluded that viability responses to mesophilic AD were determined by the interplay of AD-conditions and species- and seed-lot-specific traits, of which HS was an important but only one factor. For the use of wildflowers as biogas feedstock, we recommended long retention times and special care with regard to HS species.

Absorbed dose rate for marine biota due to the oil spilled using ICRP reference animal and Monte Carlo simulation

The current study aimed to obtain dose conversion coefficients for marine animals due to an oil spill accident using two variables: crude oil activity concentration and organism depth. Thorium series presented a dose contribution twice that uranium series for similar conditions. Bi-214 and Tl-208 stood out for delivering a higher dose rate for uranium and thorium series, respectively. Results obtained can be used to assess the maximum exposure time for emergency oil control, removal, and mitigation in an oil spill accident.

Analysis of The Noise Level of The Diesel Engine with 1100 RPM in The Indoor Condition

One of the weaknesses of diesel engines that most users complain about is the vibration and the noise. Therefore, it is very important to know the noise level of an engine in a room to consider the allowed duration of the exposure time, which is the aim of this study. The instrument used in this study was the Sound Level Meter, by first determining the radius of the hemisphere used in determining the location for the data collection. The measurement was carried out four times, where the largest value was considered as the main data, at four points. The result in this study indicated that the noise level of the diesel engine with a speed of 1100 rpm was 92.805 dBA with the background noise in the diesel engine room of 51.6 dB. Based on government regulations, the maximum exposure time to the noise at this level is 2 hours.

Thermo-physical evaluation of firefighter outer garment in high flux environments

Thermal protective performance tests have been conducted and improved over the years to assess the safety provided by firefighters’ outer thermal garments. Existing evaluation criteria based on empirical relations require an iterative process to estimate skin burn injuries. In this work, the concept of critical time – maximum exposure time before physical failure, is proposed, and utilized to abate this iterative process. The critical time relation to the fabric performance is investigated at an incident heat flux of 41, 84 and 126 kW/m2. Furthermore, parametric studies are performed to characterize the fabric thermo-physical behavior and associated burn degree. The tested specimens consist of an outer shell, a moisture barrier and a thermal liner. The methodology of visual assessment as per ISO 6942 is implemented to approximate the critical time. The critical time relation to increasing incident heat flux displayed a nonlinear performance reduction in the garment. An increase in the second degree burn time was observed for a vertically oriented bench-scale test. The firefighter’s current outer garment failed at a high flux of 126 kW/m2. The concept of relating the critical time to cumulative incident flux will aid the education of firefighters on fluctuating fire environments. This research opens a new domain to analyse the protective garments utilising the critical time.