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A computational fluid dynamics (CFD) simulation was developed to simulate an industrial cheese chilling process. Forced air chilling experiments were performed on blocks of agar (cheese analogue) to simulate the airflow and product arrangement in a section of an industrial cheese chilling tunnel. The flow field was solved at steady-state and decoupled from the heat transfer processes. The six blocks of agar were placed in a polystyrene test chamber that was in turn placed in an environmental testing chamber. Temperatures were measured at the surfaces and the geometric centre of the tested blocks of agar. Good agreement was observed between predicted and experimental data. Having been validated, the model was used to generate simple correlation models for predicting the volume-averaged temperature of blocks of cheddar cheese and mozzarella cheese during industrial chilling

BackgroundOxygen-delivering modalities like humidified high-flow nasal cannula (HFNC) and noninvasive positive-pressure ventilation (NIV) are suspected of generating aerosols that may contribute to transmission of disease such as coronavirus disease 2019. We sought to assess if these modalities lead to increased aerosol dispersal compared to the use of non-humidified low-flow nasal cannula oxygen treatment (LFNC).MethodsAerosol dispersal from 20 healthy volunteers using HFNC, LFNC and NIV oxygen treatment was measured in a controlled chamber. We investigated effects related to coughing and using a surgical face mask in combination with the oxygen delivering modalities. An aerodynamic particle sizer measured aerosol particles (APS3321, 0.3–20 µm) directly in front of the subjects, while a mesh of smaller particle sensors (SPS30, 0.3–10 µm) was distributed in the test chamber.ResultsNon-productive coughing led to significant increases in particle dispersal close to the face when using LFNC and HFNC but not when using NIV. HFNC or NIV did not lead to a statistically significant increase in aerosol dispersal compared to LFNC. With non-productive cough in a room without air changes, there was a significant drop in particle levels between 100 cm and 180 cm from the subjects.ConclusionsOur results indicate that using HFNC and NIV does not lead to increased aerosol dispersal compared to low-flow oxygen treatment, except in rare cases. For a subject with non-productive cough, NIV with double-limb circuit and non-vented mask may be a favourable choice to reduce the risk for aerosol spread.

Recent research into emissions of (semi-)volatile organic compounds [(S)VOC] from solid materials has focused on the development of suitable reference materials for quality assurance/quality control of emission test chamber measurements, which fulfill requirements such as homogenous and reproducible (S)VOC release. The approach of this study was to find a method for preparation of a material with predictable (S)VOC emission rates. A VOC (styrene) and an SVOC (2,6-diisopropylnaphthalene, DIPN), loaded into either vacuum grease or a 1:1 mixture of paraffin/squalane, have been tested. For the prediction of the emission rates, a model using the finite element method (FEM) was created to simulate the (S)VOC emission profiles. Theoretical and experimental results obtained in a Micro-Chamber/Thermal Extractor (μ-CTE™) and in 24 L emission test chamber measurements were in good agreement. Further properties were investigated concerning the material applicability, such as shelf life and inter-laboratory comparability. The maximum relative standard deviation in the inter-laboratory study was found to be 20%.

The test chamber in an open-loop wind tunnel is a critical part for aerodynamic experiment. The study aims to assess the feasibility of the new design of test chamber for open–loop wind tunnel by studying the fluid characteristic and the average pressure in the test chamber. The study is done by a series experimental test for the test chamber. From experimental test, the downstream velocity in the test chamber is increased from 8.9 m/s to 12.72 m/s where the pressure gradient is ranging from 6.19 to 8.398 atm with the overall turbulence intensity for the test chamber is 0.749%. According to the results, the designed open-loop wind tunnel is acceptable to use for an aerodynamic test.

The objective of this study is to understand the effect of indoor air stability on personal exposure to infectious contaminant in the breathing zone. Numerical simulations are carried out in a test chamber with a source of infectious contaminant and a manikin (Manikin A). To give a good visual illustration of the breathing zone, the contaminant source is visualized by the mouth of another manikin. Manikin A is regarded as a vulnerable individual to infectious contaminant. Exposure index and exposure intensity are used as indicators of the exposure level in the breathing zone. The results show that in the stable condition, the infectious contaminant proceeds straightly towards the breathing zone of the vulnerable individual, leading to a relatively high exposure level. In the unstable condition, the indoor air experiences a strong mixing due to the heat exchange between the hot bottom air and the cool top air, so the infectious contaminant disperses effectively from the breathing zone. The unstable air can greatly reduce personal exposure to the infectious contaminant in the breathing zone. This study demonstrates the importance of indoor air stability on personal exposure in the indoor environment and provides a new direction for future study of personal exposure reduction in the indoor environment.

SUMMARY The aim of this study was to compare the effects of accelerated aging on the overall color stability of potentially color adjusting commercial resin-based composite resins. Thirty specimens (10 mm diameter and 2.5 mm thick; n=6) were fabricated using five different materials: Estelite Omega, GC Kalore, Venus Pearl, Harmonize, and Omnichroma. Color measurements were taken for each sample using a spectrophotometer before and after submitting samples through the artificial aging process (Q-sun Xenon Test Chamber, 102 min light at 63°C black panel temperature; 18 min light and water spray per ASTM G155) for a total of 300 hours (12.5 days). The total color difference (ΔE*ab) was calculated using SpectraMagic NX software and analyzed using one-way analysis of variance and Tukey test. The results for color change (ΔE*ab) were statistically significant. Omnichroma and Venus Pearl presented superior color stability and the lowest overall color change, whereas GC Kalore and Harmonize presented significant color change that would be considered clinically unacceptable (ΔE*ab > 3.3).

Rinko Akamine, Naomi Miyamoto, Shoko Kiritoshi, Mami Kusaka, Masayuki Akimoto Osaka Red Cross Hospital, Osaka, JapanCorrespondence: Masayuki AkimotoOsaka Red Cross Hospital, 5-30 Fudegasakicho, Tennojiku, Osaka, 543-8555, JapanEmail masayuki@akimoto3.comBackground: We previously reported a novel technique using an elastic silicone bowl, which was handmade from a phaco test chamber, to salvage dislocated lenses and perform phacoemulsification and aspiration (PEA) on the bowl. However, creating the bowl was challenging.Methods: A factory-made elastic silicone sheet (ESS), a ready-to-use alternative for the posterior capsule of the lens, was prepared. We used this sheet to salvage and support the dislocated/subluxated lenses in 11 eyes of nine patients.Results: We could use a sheet immediately after we opened the package. In all the cases, we could insert a sheet beneath the lens and PEA performed at the center of the operative field. There was only one incident where the lens could not be placed onto the disc at the first attempt, but the lens was eventually salvaged. There was no risk of rupture during PEA, and the ESS could be removed completely without any complications.Conclusion: The factory-made ESS described here can be used for salvaging dislocated/subluxated lenses and safely performing PEA.Keywords: lens dislocation, perfluorocarbon, alternative posterior capsule of the lens

Lack of attention to the effect of laboratory conditions on the results of asphalt mixture tests, especially these of the warm mix asphalt (WMA), makes the analysis of results misleading. Thus herein, after examining the research on WMA and factors affecting test results in laboratory conditions, the effect of three parameters including short-term aging (asphalt binder storage in the oven), curing time (from construction to placement in the test chamber), and thermal equilibrium time (from placement in the test chamber to the test onset) were investigated on the characteristics of WMA at mid-temperature. To simultaneously examine these three factors, 36 modes were developed to evaluate their effect on the stiffness modulus and fatigue cracking, using the indirect tensile stiffness modulus test (ITSM) and indirect tensile fatigue test (ITFT), respectively. Results of the experiments showed that increasing the time of asphalt binder placement in the oven for 2–6 h significantly increased the stiffness modulus of the mixture, which reduced the fatigue life of the WMA. With increasing the curing time and improving the adhesion between asphalt binder and aggregates, the stiffness modulus and fatigue life of the specimens increased; however, by increasing the thermal equilibrium time, the stiffness modulus and fatigue life of the specimens decreased due to asphalt binder viscoelastic behavior and temperature sensitivity. Results of statistical analyses revealed that short-term aging, curing time, and thermal equilibrium time in laboratory conditions were effective on the stiffness modulus and fatigue life of WMA at a 95% confidence level.

Hydrocarbons are being considered as an energy efficient alternative substance to HCFC-22 in ACs. Better thermo physical properties of HCs results higher energy efficiency in split air conditioners than HCFC-22. However, safety of HC substances needs to be addressed when it is used in ACs. This paper focus on a typical inverter operated SAC with 5.2 kW nominal cooling capacity for performance evaluation. Various tests have been carried out on SAC in well-equipped psychrometric test chamber maintaining test conditions as prescribed in Indian Standard (BIS 1391 part-1) for full capacity and half capacity of test unit. Initially HCFC-22 was tested to establish baseline performance. HCs chosen are HC-290 and its blend (50% HC-290 and 50% HC-1270 by weight) were tested for as a drop-in replacement for HCFC-22. Indian SEER of SAC with HC-290/HC-1270 blend achieved was 4.91 as against 5.11 for HC-290. For HC-290 and HC-290/HC-1270 blend, ISSER is about 20.2% and 15.5% higher respectively than HCFC-22.

Purpose This paper aims to study and assess a new approach for prediction of changes of pressure during gas discharge inside the room protected by fixed gaseous extinguishing system by computational fluid dynamics (CFD) simulations. Design/methodology/approach The research program consisted of two stages. The first stage was dedicated to the experimental measurements of pressure changes during extinguishing gas discharge into the test chamber in a real scale (70 m3), for two relief openings that differ in their area. The next step was about performing CFD simulations forecasting pressure changes during gas discharge into the numerically represented test chamber. Estimation of the correctness and usefulness of the CFD model was based on a comparison of the CFD results with standard calculations and experimental measurements. Findings Numerical modelling of pressure changes during the carbon dioxide discharge was very close to the experiment. The obtained results had sufficient accuracy (in most cases relative error Originality/value Conducted research confirms the viability of the new approach in modelling the pressure changes and indicates additional benefits of the numerical analyses in the determination of the fire safety of protected premises.

The article presents the methodology of testing sliding bearings with a flexible shell, focusing on the issue of temperature increase during experiments for a specific time interval of the START-STOP test cycle. Selected material pairs, used in previous studies, were used in the experiment. The stand used for tests in the start-stop cycle was developed under the project POIG.01.03.01-00-027 / 08-00 at the Faculty of Technical Sciences UWM in Olsztyn.

There are no ASHRAE/HVI standards for characterizing or specifying acceptable values of capture efficiency (CE) (i.e. percentage of cooking-contaminants captured/exhausted by a household rangehood)...

Inhalation doses due to radon and thoron are predominantly due to the inhalation of progeny of Radon and Thoron. The progeny/decay-products of radon and thoron are particulates unlike their parent gas and exhibit different physical properties like attachment to the aerosols and deposition on different surfaces. All these properties in turn depend on the environmental conditions such as air velocity, aerosol concentration, attachment rate, etc. The role of air velocity on deposition on surfaces decides the progeny particles left in the air for inhalation. Therefore, in the present work, we have studied the effect of air velocity on the inhalation dose due to radon and thoron progeny at the centre of a 0.5-m3 calibration chamber as well as on all surfaces. Hence, the studies were carried out at different air velocities, and inhalation doses were measured using deposition-based direct radon and thoron progeny sensors.

Purpose: In this paper, in vivo methods of estimation of the shear modulus and hydraulic permeability of subcutaneous tissue of lower limb are presented. Methods: The experimental technique is based on single- or two-chamber inflation-deflation tests in which temporal changes in limb circumference under the test chamber for cyclic loading are registered. Simplified models for fast undrained deformation and slow creep of oedematous tissue with squeezing out interstitial liquid were considered. Finite element simulations of the chamber test within a finite deformation poroelastic model were elaborated. Results: Formulas necessary to estimate the shear modulus and permeability of subcutaneous tissue were derived and then tested or calibrated using the results of poroelastic simulations. An example of application of the derived formulas for clinical data obtained from the chamber test was discussed. Conclusions: A simple in vivo methods of estimation of the hydromechanical properties of lymphedematous tissue (shear modulus and permeability) were proposed. The strengths and weaknesses of the proposed methodology were discussed.

The resonant frequency of the quartz resonator is related to the ambient temperature. This paper designs an automatic test system for frequency-temperature characteristics of quartz resonator cluster. The system based on FPGA(field programmable gate array) and temperature sensor collects the resonant frequency and ambient temperature. It combines computer and FPGA to obtain 6 resonator frequency values and 1 temperature value per second by polling. Applying the system and the high and low temperature test chamber, the resonant frequency of the cluster quartz resonator at different temperatures can be obtained in real time, which greatly improves the measurement accuracy and density of the data.

Rats emit a variety of calls in the 40–80 kHz range (50 kHz calls). While these calls are generally associated with positive affect, it is unclear whether certain calls might be used selectively in certain contexts. To examine this, we looked at ultrasonic calls in 30–40 day old male rats during the expectation of either play or food, both of which are reinforcing. Behavior and vocalizations were recorded while rats were in a test chamber awaiting the arrival of a play partner or food over seven days of testing. Control groups were included for the non-specific effects of food deprivation and social isolation. Play reward led to an increase in 50 kHz vocalizations, generally, with specific increases in trill and “trill with jump” calls not seen in other groups. Expectation of food reward did not lead to a significant increase in vocalizations of any type, perhaps due to the young age of our study group. Further, rats that were food deprived for the food expectation study showed markedly lower calls overall and had a different profile of call types compared to rats that were socially isolated. Taken together, the results suggest that trill-associated calls may be used selectively when rats are socially isolated and/or expecting a social encounter.

The main aim of this study was to reveal the influence of spoiler on thickness uniformity of ice layer in environmental test chamber by experiments and numeric, while analyse the effects of variable fan speed and temperature on the results parameters. The results parameters were ice thickness and ice shape. The second aim was to study the effect of different droplet sizes on ice shape. The results revealed that the droplet size had effects on the ice shape, and the spoiler had strong effects on the ice uniformity: (1) The spoiler could significantly affected the trajectory of the droplets by disturbing the air flow, and then improved the ice thickness uniformity; (2) Increasing the fan speed could effectively increase the ice thickness in a limited time; (3) The droplet size had a direct impact on the ice shapes, and different droplet sizes would result in different ice shapes; (4) Temperature also has an important impact on the ice shape, and account for the formation of different ice shapes, the dual effects of temperature and droplet size should be considered comprehensively. The experience results provide the theoretical and engineering technical bases and prevents the occurrence of owe experiment in the atmospheric icing laboratory.