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Existing research on PTFE-based reactive materials (RMs) mostly focuses on Al/PTFE RMs. To explore further possibilities of formulation, the reactive metal components in the RMs can be replaced. In this paper, Zr/PTFE and Ti/PTFE RMs were prepared by cold isostatic pressing and vacuum sintering. The static and dynamic compressive mechanical properties of Zr/PTFE and Ti/PTFE RMs were investigated at different strain rates. The results show that the introduction of zirconium powder and titanium powder can increase the strength of the material under dynamic loading. Meanwhile, a modified J-C model considering strain and strain rate coupling was proposed. The parameters of the modified J-C model of Zr/PTFE and Ti/PTFE RMs were determined, which can describe and predict plastic flow stress. To characterize the impact-induced reaction behavior of Zr/PTFE and Ti/PTFE RMs, a quasi-sealed test chamber was used to measure the over-pressure induced by the exothermic reaction. The energy release characteristics of both materials were more intense under the higher impact.

This article deals with volatile organic substances (VOCs) and odours that can be released into the indoor environment from synthetic leathers that are part of upholstered furniture. The primary task of this study was to provide a detailed analysis of selected synthetic leathers and assess their emission characteristics, including odour substances. VOC emissions were determined using the test chamber method (ČSN EN ISO 16000-9) at a temperature of 23oC and a relative humidity of 50%. The emitted compounds were adsorbed by standard stainless steel tubes with Tenax TA sorbent. VOCs were analysed by thermal desorption and gas chromatography with mass spectrometry The properties of odours were tested using a Sniffer 9000 device, which was directly connected to a gas chromatograph with a flame ionization detector. The dominant substances (with the highest concentration) that were emitted by samples of tested synthetic leathers include toluene (118.2 µg.mMINUS SIGN 3), 1,2-propanediol (46.2 µg.mMINUS SIGN 3), and limonene (153.0 µg.mMINUS SIGN 3). Ohio synthetic leather produced the most unpleasantness hedonic tone (-4) from all evaluated materials.

Formaldehyde is considered as carcinogenic and is emitted from particleboards and plywood used in toy manufacturing. Currently, the flask method is frequently used in Europe for market surveillance purposes to assess formaldehyde release from toys, but its concordance to levels measured in emission test chambers is poor. Surveillance laboratories are unable to afford laborious and expensive emission chamber testing to comply with a new amendment of the European Toy Directive; they need an alternative method that can provide reliable results. Therefore, the application of miniaturised emission test chambers was tested. Comparisons between a 1 m3 emission test chamber and 44 mL microchambers with two particleboards over 28 days and between a 24 L desiccator chamber and the microchambers with three puzzle samples over 10 days resulted in a correlation coefficient r2 of 0.834 for formaldehyde at steady state. The correlation between the results obtained in microchambers vs. flask showed a high variability over 10 samples (r2: 0.145), thereby demonstrating the error-proneness of the flask method in comparison to methods carried out under ambient parameters. An exposure assessment was also performed for three toy puzzles: indoor formaldehyde concentrations caused by puzzles were not negligible (up to 8 µg/m3), especially when more conservative exposure scenarios were considered.

Active disturbance rejection control (ADRC) emerges as a promising control approach due to its partial model-based characteristics and strong disturbance rejection capabilities. Nevertheless, it is a difficult problem to tune various parameters of ADRC in practical applications. To address the challenge of parameter tuning, this work develops a parameter self-tuning rule based on spatial–temporal scale transformations to simplify the tuning process and enhance its control performance. In particular, based on the transformations of spatial–temporal scale, the parameter tuning relationships for ADRC’s components, including tracking differentiator (TD), extended state observer (ESO) and feedback controller, are provided for a second-order nonlinear system. Numerical simulations show that the proposed method can conveniently and effectively provide a set of well-tuned parameters for ADRC to boost the efficiency of control. Finally, the proposed parameter tuning rule is applied to the intake pressure control of the flight test chamber system, further validating its effectiveness. The results demonstrate that the ADRC with the proposed parameter self-tuning method significantly improves the precision of the intake pressure under different operating conditions, thereby ensuring the reliability of aeroengine flight tests.

In order to estimate the resuspension of the particles empirically, it is necessary to carry out a homogeneous distribution of the particles on the tested surfaces. Thus, in many studies, seeding or deposition in experimental chambers is performed to quantify initial concentrations for subsequent resuspension experiments. The current study was carried out to assess metal particle seeding efficiency on four types of urban surfaces (slate, facade coating, tile, and glass) in a test chamber. To achieve this objective, we compared firstly different solubilization techniques of silver polydisperse particles (1.3–3.2 μm and 0.5–1.0 μm) and gold polydisperse particles (Ø˂5 μm) for chemical quantification by ICP-MS. The result showed better yields in the case of gold for all solubilization techniques studied (82% ± 5% to 98% ± 2% for gold versus 23% ± 18% to 84% ± 12% for silver). Based on this result, four seeding tests were carried out with the gold particles (distribution in chamber centered on 1μm). The concentrations seeded on urban surfaces (mean ± SD) varied from 10,900 ± 1,900 μg.m −2 (facade coating sample) to 1900 ± 390 μg.m −2 (glass sample). The relative standard deviation of the measured concentrations equaled 9.5% (tested for aluminum foils), which was less than the measurement uncertainty of the recording equipment (≈14%) and reflected good seeding homogeneity. Observations by scanning electron microscopy coupled to microanalysis (SEM-EDX) were in agreement with these conclusions.

Emphasis has been given to the reliability of a wide range of equipment in recent years. However, the reliability of environmental test chambers has received little research attention. In this paper, the Bayesian network (BN) model is proposed to evaluate the reliability of the chambers for the first time. This paper is an important supplement to reliability research on test chambers, and it proposes a novel reliability assessment approach that involves the following: (1) the maximum information coefficient is used to select components that are particularly important for system failures; (2) failure mode and effect analysis and fault tree analysis are used to initially establish the logical relationship between components; (3) max-min hill-climbing algorithm is used to learn the final BN structure; and (4) the Poisson process is introduced to calculate the failure probability of these components. Results show that BN describes the directional and quantitative dependencies between components in more detail than fault tree does. The failure rate predicted by BN is consistent with the actual data, and the determination coefficient (R2) is 0.6. At present, the mean time between failures of a single chamber is approximately 20 days. According to the reliability threshold, the cumulative failure times of the chambers can be predicted, and most of the forecast errors are within 6 days. When the chambers fail, the structural importance of the components is shown, and a reasonable fault diagnosis sequence is provided by the proposed BN model.

Thermal switches have gained intense interest recently for enabling dynamic thermal management of electronic devices and batteries that need to function at dramatically varied ambient or operating conditions. However, current approaches have limitations such as the lack of continuous tunability, low switching ratio, low speed, and not being scalable. Here, a continuously tunable, wide-range, and fast thermal switching approach is proposed and demonstrated using compressible graphene composite foams. Large (~8x) continuous tuning of the thermal resistance is achieved from the uncompressed to the fully compressed state. Environmental chamber experiments show that our variable thermal resistor can precisely stabilize the operating temperature of a heat generating device while the ambient temperature varies continuously by ~10 °C or the heat generation rate varies by a factor of 2.7. This thermal device is promising for dynamic control of operating temperatures in battery thermal management, space conditioning, vehicle thermal comfort, and thermal energy storage. Current designs of thermal switches are limited by a lack of continuous tunability, low switching ratio, low speed, and not being scalable. Here the authors report a continuously tunable, wide-range, fast, and cost effective thermal switching approach that is demonstrated using compressible graphene composite foams.

With reference to the international standard ISO16000-9 and the national standard GB/T 31106-14, this paper has chosen leather seats as the research object in order to study the emission of volatile organic compounds (VOCs) and total volatile organic compound (TVOC). The test results show that about 21 species of VOCs released from the leather seats were measured, including several types of aldehydes, ketones, aromatic hydrocarbon ,hydrocarbon, lipids and so on.This paper analysis the possible sources of volatile organic compounds in leather seats as well.

Real-time, online measurements of atmospheric organic aerosol (OA) composition are an essential tool for determining the emissions sources and physicochemical processes governing aerosol effects on climate and health. However, the reliance of current techniques on thermal desorption, hard ionization, and/or separated collection/analysis stages introduces significant uncertainties into OA composition measurements, hindering progress towards these goals. To address this gap, we present a novel, field-deployable extractive electrospray ionization time-of-flight mass spectrometer (EESI-TOF), which provides online, near-molecular (i.e., molecular formula) OA measurements at atmospherically relevant concentrations without analyte fragmentation or decomposition. Aerosol particles are continuously sampled into the EESI-TOF, where they intersect a spray of charged droplets generated by a conventional electrospray probe. Soluble components are extracted and then ionized as the droplets are evaporated. The EESI-TOF achieves a linear response to mass, with detection limits on the order of 1 to 10 ng m−3 in 5 s for typical atmospherically relevant compounds. In contrast to conventional electrospray systems, the EESI-TOF response is not significantly affected by a changing OA matrix for the systems investigated. A slight decrease in sensitivity in response to increasing absolute humidity is observed for some ions. Although the relative sensitivities to a variety of commercially available organic standards vary by more than a factor of 30, the bulk sensitivity to secondary organic aerosol generated from individual precursor gases varies by only a factor of 15. Further, the ratio of compound-by-compound sensitivities between the EESI-TOF and an iodide adduct FIGAERO-I-CIMS varies by only ±50 %, suggesting that EESI-TOF mass spectra indeed reflect the actual distribution of detectable compounds in the particle phase. Successful deployments of the EESI-TOF for laboratory environmental chamber measurements, ground-based ambient sampling, and proof-of-concept measurements aboard a research aircraft highlight the versatility and potential of the EESI-TOF system.

The formation of secondary organic aerosol (SOA) from the oxidation ofβ-pinene via nitrate radicals is investigated in the Georgia Tech Environmental Chamber (GTEC) facility. Aerosol yields are determined for experiments performed under both dry (relative humidity (RH) < 2 %) and humid (RH = 50 % and RH = 70 %) conditions. To probe the effects of peroxy radical (RO2) fate on aerosol formation, “RO2+NO3 dominant” and “RO2+HO2 dominant” experiments are performed. Gas-phase organic nitrate species (with molecular weights of 215, 229, 231, and 245 amu, which likely correspond to molecular formulas of C10H17NO4, C10H15NO5, C10H17NO5, and C10H15NO6, respectively) are detected by chemical ionization mass spectrometry (CIMS) and their formation mechanisms are proposed. The NO+ (at m/z 30) and NO2+ (atm/z 46) ions contribute about 11 % to the combined organics and nitrate signals in the typical aerosol mass spectrum, with the NO+ : NO2+ ratio ranging from 4.8 to 10.2 in all experiments conducted. The SOA yields in the “RO2+NO3 dominant” and “RO2+HO2 dominant” experiments are comparable. For a wide range of organic mass loadings (5.1–216.1 µg m-3), the aerosol mass yield is calculated to be 27.0–104.1 %. Although humidity does not appear to affect SOA yields, there is evidence of particle-phase hydrolysis of organic nitrates, which are estimated to compose 45–74 % of the organic aerosol. The extent of organic nitrate hydrolysis is significantly lower than that observed in previous studies on photooxidation of volatile organic compounds in the presence of NOx. It is estimated that about 90 and 10 % of the organic nitrates formed from the β-pinene+NO3 reaction are primary organic nitrates and tertiary organic nitrates, respectively. While the primary organic nitrates do not appear to hydrolyze, the tertiary organic nitrates undergo hydrolysis with a lifetime of 3–4.5 h. Results from this laboratory chamber study provide the fundamental data to evaluate the contributions of monoterpene+NO3 reaction to ambient organic aerosol measured in the southeastern United States, including the Southern Oxidant and Aerosol Study (SOAS) and the Southeastern Center for Air Pollution and Epidemiology (SCAPE) study.