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Abnormal heating will reduce the insulation performance of composite insulators or even cause insulator fracture, and the abnormal heating phenomenon is more serious under high-humidity conditions. Therefore, in this paper, the voltage withstand test of abnormal heating composite insulators caused by aging and damp sheath, decay-like core rod, and contamination were carried out under different ambient humidity. The heating and discharge of composite insulators were observed by infrared thermal imager and ultraviolet imager, and its temperature characteristics were analyzed from the aspects of heating range, heating shape, and temperature difference. In addition, in order to study the abnormal heating mechanism of composite insulators, the micro-morphology, chemical groups and dielectric properties of the silicon rubber of composite insulators with aging and damp sheath and the decay-like core rod were also measured. It is found that the temperature characteristics of the three types of abnormal heating composite insulators are different, and the temperature difference increases with the increase of humidity. The deterioration of silicone rubber and core rod material is the internal reason for the abnormal heating of composite insulators, and high-humidity conditions will exacerbate the heating phenomenon. [ABSTRACT FROM AUTHOR]

Abnormal heating will reduce the insulation performance of composite insulators or even cause insulator fracture, and the abnormal heating phenomenon is more serious under high-humidity conditions. Therefore, in this paper, the voltage withstand test of abnormal heating composite insulators caused by aging and damp sheath, decay-like core rod, and contamination were carried out under different ambient humidity. The heating and discharge of composite insulators were observed by infrared thermal imager and ultraviolet imager, and its temperature characteristics were analyzed from the aspects of heating range, heating shape, and temperature difference. In addition, in order to study the abnormal heating mechanism of composite insulators, the micro-morphology, chemical groups and dielectric properties of the silicon rubber of composite insulators with aging and damp sheath and the decay-like core rod were also measured. It is found that the temperature characteristics of the three types of abnormal heating composite insulators are different, and the temperature difference increases with the increase of humidity. The deterioration of silicone rubber and core rod material is the internal reason for the abnormal heating of composite insulators, and high-humidity conditions will exacerbate the heating phenomenon.

Polymer‐in‐salt‐electrolytes (PISEs) are an important class of electrolytes as they carry the promise of faster and single ion transport. Unfortunately, due to unavailability of a suitable polymer host PISE has still not reached to commercial level. In the present work, using a novel synthesis protocol developed by the group, glutaraldehyde crosslinked wheat starch has been successfully modified with sodium iodide (NaI) to synthesize a flexible PISE membrane with desired electrochemical properties. Present paper reports the effect of crosslinker and exposure to high humidity ambience on electrochemical and morphological properties. It has been established that on exposure to higher humidity atmosphere starch‐based PISEs stabilize at lower resistance value, but with higher ion relaxation time, which indicates that effect of high humidity treatment is more on salt dissociation instead of assisting the ion transport. The studied materials have conductivity ≈0.01 S cm−1 range with ESW >2.5 V, ensuring its usability in electrochemical devices. The developed synthesis protocol does not require any complicated synthesis route and/or sophisticated instrument hence the overall process is economical also, adding up to its potentiality for energy device fabrication. [ABSTRACT FROM AUTHOR]

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A general two-step method combining dip coating and light curing process was used to prepare polyvinylpyrrolidone hydrophilic lubricating coatings on the surface of polyurethane sheets. It was found that the ambient humidity (water vapor) and water content of the coating solution can have a great influence on the lubricating performance of the coating during the preparation of hydrophilic coatings. Compared with the environmental conditions of lower humidity (30%RH), the friction coefficient of the coatings prepared under high humidity (70%RH) decreased significantly, from 0.183 to 0.035 on average. Under the same humidity, changing the proportion of water in the top coating solution, the lubricating properties of the coatings also show great differences. At 30%RH, with the increase of water content in the top coating solution, the average friction coefficient of the coating gradually decreased from 0.183 at 0 wt% water content to 0.043 at 20 wt% water content. When the proportion of water in the solvent exceeds a certain amount, the lubricity of the coating will change in the opposite direction. The evaporation process of top coating solvent under different conditions shows the possible influence of water on the coating lubricating performance during coating preparation. [ABSTRACT FROM AUTHOR]

The drop in internal relative humidity (IRH) affects the early-age cracking risk of concrete. Superabsorbent polymers (SAPs), an internal curing material, are usually used to decrease the drop rate of IRH in concrete and the shrinkage-induced cracking risk of concrete. This study investigated the changes in IRH and distribution of IRH in SAP-modified concrete under sealed conditions and exposed to various ambient humidities. The test results showed that the use of SAPs and additional internal curing water can compensate for water consumption caused by self-desiccation and moisture diffusion (MD) and increase the IRH of concrete exposed to various ambient humidities. However, the degree to which SAPs mitigated the drop in IRH of concrete exposed to outside ambient decreased with increasing ambient humidity. The IRH of SAP-modified concrete increased, and the MD coefficient decreased nonlinearly with increasing ambient humidity. A model for predicting IRH of SAP-modified concrete exposed to various ambient humidities under the influence of self-desiccation and MD was proposed. [ABSTRACT FROM AUTHOR]

Polyether ether ketone (PEEK) is one of the representatives of special engineering plastics. Due to the high molding temperature, the molding method of ordinary plastics and cavity abrasives are difficult to meet the requirements. In view of this, pure PEEK was prepared by vacuum hot pressing sintering technology at different sintering temperatures. The mechanical properties and microstructure characterization results showed that the pure PEEK prepared at 350 °C showed excellent friction and wear properties. Then PEEK and CF/PEEK composites were prepared at the optimum sintering temperature. The friction experiments of prepared materials were carried out using UMT-2. The effects of ambient humidity on the tribological properties, wear mechanism and antistatic properties of prepared materials were systematically studied. The surface analysis and properties of the materials were measured by 3D profiler, scanning electron microscope, friction electrostatic tester. The results showed that friction coefficient of PEEK and CF/PEEK composite changed slightly with increase of ambient humidity. The wear rate of PEEK decreased firstly and then increases, which reached the lowest of 3.09 × 10−5 mm3/Nm when the ambient humidity was 40%. The wear rate of CF/PEEK composite changed slightly, which was significantly lower than that of PEEK, and the main wear mechanism was adhesive wear. The surface friction static electricity of PEEK and CF/PEEK composites decreased with the increase of humidity.

The article presents the results of research on the influence of the natural moisture of a filament made of acrylonitrile–butadiene–styrene terpolymer (ABS) on the mechanical properties and quality of products fabricated with fused filament fabrication (FFF). The concept of the natural moisture of the filament was defined, and the range of its variability was identified in reference to the range of the natural ambient humidity. It is shown that a change in the ambient humidity by 10% resulted in a change in filament moisture by about 0.05%. The results of the research on the moisture variability of an ABS filament stored in a package, an airtight container, or a container with a moisture absorber are also discussed. The last part of the article presents the results of the research on the impact of the moisture of the filament in its natural range of variability on select mechanical properties of filaments and products made using FFT. It is shown that this impact was significant and had a value of 1 MPa on 0.1% filament moisture. [ABSTRACT FROM AUTHOR]

Ambient humidity is an important factor to consider when maintaining dielectric films' component performance. Herein, humidity-influenced experiments were conducted on complex spectral dielectric films based on SiO2 and K9 substrates. Firstly, complex spectral dielectric films' spectral and surface stresses in different humidity environments were measured. Subsequently, laser-induced damage threshold measurements were carried out on these components. The experimental results indicate that the environmental humidity will induce the evolution of the internal structure of the dielectric films on the mirror, resulting in the deformation of the coating surface and a slight shift of the reflection spectrum. At the same time, the environmental humidity also greatly influences the anti-laser damage performance of the dielectric film mirror. Dielectric films based on SiO2 have excellent damage resistance in high-humidity environments. Conversely, K9-based dielectric films have better damage resistance in low-humidity environments. [ABSTRACT FROM AUTHOR]

This study explores the friction and wear performance of brake materials for new energy micro logistics vans under different ambient temperature (3 °C, 23 °C, 43 °C) and humidity conditions (35 %, 65 %, 95 %) using pin-disc experimental device. The findings reveal that at 3 °C, the friction coefficient exhibits extreme sensitivity to changes in humidity, with a significant reduction as humidity increases. Simultaneously, the increase of humidity leads to the transition from adhesive wear to abrasive wear and fatigue wear. At room temperature (23 °C) and 43 °C, humidity has minimal impact on the friction coefficient; however, higher humidity promotes oxidation film formation on the friction surface leading to dominant oxidation wear. Notably, in low-humidity environments, temperatures at 3 °C and 43 °C cause severe brake pad wear. The severity is greater at 43 °C because the resin-based components within the brake pad material decompose at elevated temperatures. Under such circumstances, appropriately increased humidity helps mitigate brake pad wear rates. However, too much humidity can increase fatigue wear of brake pad materials. • At 3 °C, the friction coefficient is extremely sensitive to humidity, significantly decreasing as humidity rises. • In high humidity (95 %) environments, moisture plays a dual role in wear. • At room temperature (23 °C) and medium humidity (65 %), the brake material has good friction and wear properties. [ABSTRACT FROM AUTHOR]

Concrete material properties are affected by humidity and have swelling properties. For cross-sea bridges, high arch dams, marine platforms, etc. that work in the water environment all the year round, as well as concrete structures soaked in floods, the environmental humidity will inevitably cause the moisture content of concrete materials and structures to change, thereby affecting the performance of concrete materials and structures. Therefore, it is particularly important to carry out research on the influence of moisture content on concrete materials and structural properties. At present, there are few studies on the effect of humidity on the mechanical properties of concrete structures. This paper mainly analyzes the influence of moisture content on the elastic modulus of concrete materials by combining theory and experiment. Studies have shown that under the same concrete strength grade and curing conditions, the moisture content of concrete specimens increases rapidly with the increase of immersion time before 2.5h, and tends to be stable after 90h, and the saturated moisture content is about 3.5%. The water content of high concrete is slower than that of concrete with low strength grade, the rate of increase of water content increases with the increase of the specific surface area of the specimen. There is a linear relationship between the elastic modulus of concrete under compression and the moisture content. [ABSTRACT FROM AUTHOR]

Mechanochemical reactions of the GaN-Al2O3 interface offer a novel principle for scientific and technological merits in the micro-/nano-scale ultra-precision surface machining. In this work, the mechanochemical reactions on Ga- and N-faced GaN surfaces rubbed by the Al2O3 nanoasperity as a function of the environmental humidity were investigated. Experimental results indicate that the N-face exhibits much stronger mechanochemical removal over the relative humidity range of 20%–80% than the Ga-face. Increasing water molecules in environmental conditions significantly promotes the interfacial mechanochemical reactions and hence accelerates the atomic attrition on N-face. The hypothesized mechanism of the selective water-involved mechanochemical removal is associated with the dangling bond configuration, which affects the mechanically-stimulated chemical reactions via altering the activation energy barrier to form the bonding bridge across the sliding interface. These findings can enrich the understanding of the underlying mechanism of mechanochemical reactions at GaN-Al2O3 interface and a broad cognition for regulating the mechanochemical reactions widely existing in scientific and engineering applications. [ABSTRACT FROM AUTHOR]

Abnormal heating of composite insulators of high-voltage transmission lines concentrate at its end, especially in a high-humidity environment. In order to study the influence of end-sheath aging and moisture absorption on abnormal heating of composite insulators, in this paper, we first discuss the appearance test, temperature rise test, and dielectric characteristic test conducted on 110 kV decommissioned composite insulators. Test results indicated the temperature rise in composite insulators increased with ambient humidity, but temperature rise was not severely affected by surface contamination of its shed and sheath; in dry environments, the dielectric constant and dielectric loss factor of high-voltage end sheaths are higher than of those of medium- and low-voltage end sheaths, and the loss effect becomes more severe after moisture absorption in a high-humidity environment. After the tests, the authors established a COMSOL simulation model of composite insulators, to analyze changes in the electric field and thermal field of the end sheath of composite insulators due to the coupling of electric and thermal fields. It was concluded that the dielectric constant of a high-voltage end sheath of the composite insulator increased after moisture absorption, distorting the partial electric field on the surface; meanwhile, the dielectric loss factor increased significantly after water molecules intruded into the aging layer of the sheath as polar molecules. Therefore, the dielectric loss (leakage conductance loss and lossy polarization loss) caused by aging and moisture absorption of the sheath surface under partially high field strength in the high-humidity environment was the leading cause of abnormal heating at the high-voltage end of composite insulators. The conclusion of this paper serves as an important reference for revealing the causes of abnormal heating of composite insulators in high-humidity environments and the influence mechanism of external factors on abnormal heating. [ABSTRACT FROM AUTHOR]

In order to accurately obtain the deflagration characteristic parameters of methane-air mixtures under different ambient humidity conditions, a 20 L spherical explosion vessel analysis model was established by using fluid dynamics software Fluidyn. The deflagration process of methane-air mixture was solved by changing the initial humidity in the model. The results showed that under the same ambient humidity conditions, with the increase of methane concentration, the maximum deflagration pressure and flame propagation speed both showed a trend of first increasing and then decreasing, and reached a peak near the equivalent concentration. Under the same methane concentration conditions, the increase in ambient humidity caused the peak deflagration pressure and flame propagation speed of the methane-air mixture to decrease, and extended the time to reach the maximum deflagration pressure and the time for the flame to propagate to the corresponding monitoring point. It can be seen that the increase of ambient humidity can reduce the explosion intensity of methane and prevent the flame spread to a certain extent, which can inhibit the deflagration of methane-air mixture. The overall performance is that the higher the ambient humidity is, the more significant the deflagration inhibition effect will be [ABSTRACT FROM AUTHOR]

The most sensitive spin-exchange relaxation-free (SERF) magnetometer generally requires a working temperature greater than 100∘C. To date, octadecyltrichlorosilane (OTS) coating is one of the best candidates for this temperature range. However, the performance and consistency of the OTS coatings within the alkali-metal vapor cells are still poor. In this paper, the formation of OTS coatings on borosilicate glass (BG) substrates was investigated. The effects of ambient relative humidity (RH) on the formation of OTS coatings were examined by atomic force microscopy (AFM) and contact angle measurement. The results showed that 75 % RH can improve the order of the OTS coatings and reduce the root mean square (RMS) roughness of the OTS coatings. Under three different ambient RHs, the soaking time of OTS molecules should be greater than 60 min to form complete OTS coating. [ABSTRACT FROM AUTHOR]

Ambient humidity is an important factor to consider when maintaining dielectric films’ component performance. Herein, humidity-influenced experiments were conducted on complex spectral dielectric films based on SiO2 and K9 substrates. Firstly, complex spectral dielectric films’ spectral and surface stresses in different humidity environments were measured. Subsequently, laser-induced damage threshold measurements were carried out on these components. The experimental results indicate that the environmental humidity will induce the evolution of the internal structure of the dielectric films on the mirror, resulting in the deformation of the coating surface and a slight shift of the reflection spectrum. At the same time, the environmental humidity also greatly influences the anti-laser damage performance of the dielectric film mirror. Dielectric films based on SiO2 have excellent damage resistance in high-humidity environments. Conversely, K9-based dielectric films have better damage resistance in low-humidity environments.

The article presents the results of research on the influence of the natural moisture of a filament made of acrylonitrile–butadiene–styrene terpolymer (ABS) on the mechanical properties and quality of products fabricated with fused filament fabrication (FFF). The concept of the natural moisture of the filament was defined, and the range of its variability was identified in reference to the range of the natural ambient humidity. It is shown that a change in the ambient humidity by 10% resulted in a change in filament moisture by about 0.05%. The results of the research on the moisture variability of an ABS filament stored in a package, an airtight container, or a container with a moisture absorber are also discussed. The last part of the article presents the results of the research on the impact of the moisture of the filament in its natural range of variability on select mechanical properties of filaments and products made using FFT. It is shown that this impact was significant and had a value of 1 MPa on 0.1% filament moisture.

SnO2/ZnO@ZIF‐8 core‐shell nanofibers were synthesized by electrospinning and hydrothermal etching ZnO component of SnO2/ZnO nanofibers. It is found that the ZIF‐8 coated SnO2/ZnO nanostructures are obtained, and the ZIF‐8 coating can obviously increase the specific surface area of nanofibers. H2S sensing properties of the sensors based on composite nanofibers were investigated. The results show that SnO2/ZnO@ZIF‐8 core‐shell nanostructures can not only improve the response to H2S, but also effectively reduce the interference of ambient humidity on semiconductor gas sensors. The response of the optimal sample to 5 ppm H2S can reach 202.3, which is about 19 times higher than that of pure SnO2 nanofibers. Compared with the response at the ambient humidity of 55 %RH, the response at the ambient humidity of 90 %RH can still maintain 84.7 %. Good selectivity and stability are also observed in our investigations. [ABSTRACT FROM AUTHOR]

Ambient humidity can directly affect the water balance in insects. The migratory fall armyworm, Spodoptera frugiperda Smith, has spread to more than 60 countries and regions in Africa, Asia, and Oceania that have a great difference in average ambient humidity. Understanding the effects of ambient humidity changes on its development, survival, and reproduction can help to predict its population dynamics in different habitats. Therefore, we evaluated the effects of atmospheric relative humidity (RH) on the development, survival, and reproduction and soil moisture on the pupation and emergence of fall armyworm. As a result, survival and pupal mass increased significantly with increasing RH. Among the five RHs tested, 80% RH was the most suitable for fall armyworm with the highest intrinsic rate of increase (r), finite rate of increase (λ), and net reproduction rate (R 0). The population growth at the different RHs in decreasing order was 80 > 100 > 60 > 40 > 20%. A relative moisture (RM) of soil from 6.80 to 47.59% was suitable for fall armyworm pupation, survival, and eclosion, but fall armyworm could not pupate normally in soil with 88.39 and 95.19% RM. The survival and emergence rate of fall armyworm pupae were reduced by irrigation that increased the RM after the mature larvae entered the soil. These findings may be helpful for refining laboratory rearing protocols, population forecasting, and management of fall armyworm. [ABSTRACT FROM AUTHOR]

Mechanochemical reactions at the gallium nitride-alumina (GaN–Al2O3) interface at nanoscale offer a significant beneficial reference for the high-efficiency and low-destruction ultra-precision machining on GaN surface. Here, the mechanochemical reactions on oxide-free and oxidized GaN surfaces rubbed by the Al2O3 nanoasperity as a function of the ambient humidity were studied. Experimental results reveal that oxidized GaN exhibits a higher mechanochemical removal rate than that of oxide-free GaN over the relative humidity range of 3–80%. The mechanical activation in the mechanochemical reactions at the GaN–Al2O3 interface is well-described by the mechanically-assisted Arrhenius-type kinetics model. The analysis indicates that less external mechanical activation energy is required to initiate the mechanochemical atomic attrition on the oxidized GaN surface compared with the oxide-free GaN surface. These results may not only gain a deep understanding of the mechanochemical removal mechanism of GaN but also provide the basic knowledge for the optimization of the oxidation-assisted ultra-precision machining.

An experimental study on the flow rate and atomization characteristics of a new gas–liquid two-phase flow nozzle was carried out to use high-concentration respirable dust in the workplace of high-efficiency sedimentation coal production based on the gas–liquid two-phase flow nozzle technology. The simulation roadway of dust fall in large coal mines was constructed, and the respirable rock dust produced by fully mechanized mining surfaces was chosen as the research object. The effects of humidity on the capture effect of respirable rock dust were analyzed in the experimental study. The results demonstrated that: (1) the distribution range of the particle size of fogdrops declines with the reduction in fogdrops D50, D[3,2] and D[4,3], which are produced by gas–liquid two-phase flow nozzles. (2) The initial ambient humidity in the simulated roadway was 64.8% RH. After the gas–liquid two-phase flow spray was started, the ambient humidity was elevated by 23.2 to 23.5% RH within 840s and tended to be stable and no longer grew after reaching 88.0–88.3% RH. The initial growth rate of the ambient humidity in the simulated roadway was high, and then was gradually slowed down. (3) Humidity is an important factor influencing the collection of respirable dust. The humidity at 10.0 m leeward of the dust-producing point was increased by 19.6% RH, and the sedimentation rate of respirable dust was increased by 6.73%; the two growth rates were 13.1% RH and 9.90% at 20.0 m; 16.4% RH and 15.42% at 30.0 m; 18.4% RH and 11.20% at 40.0 m. In practical applications of the gas–liquid two-phase flow nozzle in coal mining activities, attention shall be paid to not only the influences of its atomization characteristics on the capture effect of respirable dust but also the influences of the flow rate of the nozzle on the humidity of the working surface. Appropriate gas and water supply pressures shall be chosen according to the space and respirable dust concentration on the working surface to realize a better dust removal effect.

Key points: Skin wetness occurring secondary to the build‐up of sweat on the skin provokes thermal discomfort, the precursor to engaging in cool‐seeking behaviour.Associative evidence indicates that skin wetness stimulates cool‐seeking behaviour to a greater extent than increases in core and mean skin temperatures.The independent contribution of skin wetness to cool‐seeking behaviour during heat stress has never been established.We demonstrate that skin wetness augments cool‐seeking behaviour during passive heat stress independently of differential increases in skin temperature and core temperature.We also identify that perceptions of skin wetness were not elevated despite increases in actual skin wetness.These data support the proposition that afferent signalling from skin wetness enhances the desire to engage in cool‐seeking behaviour during passive heat stress. This study tested the hypothesis that elevations in skin wetness augments cool‐seeking behaviour during passive heat stress. Twelve subjects (6 females, age: 24 ± 2 y) donned a water‐perfused suit circulating 34 °C water and completed two trials resting supine in a 28.5 ± 0.4 °C environment. The trials involved a 20 min baseline period (26 ± 3% relative humidity (RH)), 60 min while ambient humidity was maintained at 26±3% RH (LOW) or increased to 67 ± 5% RH (HIGH), followed by 60 min passive heat stress (HS) where the water temperature in the suit was incrementally increased to 50 °C. Subjects were able to seek cooling when their neck was thermally uncomfortable by pressing a button. Each button press initiated 30 s of −20 °C fluid perfusing through a custom‐made device secured against the skin on the dorsal neck. Mean skin (Tskin) and core (Tcore) temperatures, mean skin wetness (Wskin) and neck device temperature (Tdevice) were measured continuously. Cool‐seeking behaviour was determined from total time receiving cooling (TTcool) and cumulative button presses. Tskin and Tcore increased during HS (P < 0.01) but were not different between conditions (P ≥ 0.11). Wskin was elevated in HIGH vs. LOW during HS (60 min: by + 0.06 ± 0.07 a.u., P ≤ 0.04). Tdevice was lower in HIGH vs. LOW at 40–50 min of HS (P ≤ 0.01). TTcool was greater for HIGH (330 ± 172 s) vs. LOW (225 ± 167 s, P < 0.01), while the number of cumulative button presses was greater from 40–60 min in HS for HIGH vs. LOW (P ≤ 0.04). Increased skin wetness amplifies the engagement in cool‐seeking behaviour during passive heat stress. Key points: Skin wetness occurring secondary to the build‐up of sweat on the skin provokes thermal discomfort, the precursor to engaging in cool‐seeking behaviour.Associative evidence indicates that skin wetness stimulates cool‐seeking behaviour to a greater extent than increases in core and mean skin temperatures.The independent contribution of skin wetness to cool‐seeking behaviour during heat stress has never been established.We demonstrate that skin wetness augments cool‐seeking behaviour during passive heat stress independently of differential increases in skin temperature and core temperature.We also identify that perceptions of skin wetness were not elevated despite increases in actual skin wetness.These data support the proposition that afferent signalling from skin wetness enhances the desire to engage in cool‐seeking behaviour during passive heat stress. [ABSTRACT FROM AUTHOR]

Climate classification for buildings plays an essential role in providing energy efficiency policies enforced through building energy standards, codes, and the related voluntary above-code programs, as well as in achieving decarbonization goals. Through an analysis of code-compliant office models in 801 locations in the US in this paper, first, a systematic difference is identified in building energy use, and its corresponding environmental footprint, in different locations within the same ranges of heating and/or cooling degree days but with different humidity conditions. The results show that the source energy consumption vary up to 1671 GJ (47%, excluding the equipment load) in two locations with the same climate zone but different moisture conditions. This is due to the deficiency of the degree days in predicting building energy consumption and results in a disproportionate assignment of energy efficiency measures. Second, besides similar trends when comparing the averages in subtypes, the variations in emissions within one climate zone and subtype can be over 10 times for CO 2 and 6 times for SO 2 as opposed to site energy consumption with less than 1.8 maximum variation, which signifies a substantial importance of geographic prioritization in carbon-neutral policies for the electricity providers along with climatic parameters. • Building energy use can significantly vary in locations with similar degree days. • There is a systematic variation in the energy use in different humidity conditions. • Emissions from energy use systematically vary in different humidity conditions. • An improved climate indexing is required to assign energy-efficiency measures. • Geographic prioritization is required for the deployment of clean energies. [ABSTRACT FROM AUTHOR]

• Effects of oxidation and humidity on THz spectroscopy of lignite were studied. • Refractive index has abnormal dispersion characteristic. • Complex refractive index shows obvious oxidation temperature dependence. • Humidity has a significant linearly effect on the THz spectroscopy of lignite. • Correction model of THz spectroscopy in humid environment was put forward. In this paper, the terahertz (THz) spectroscopy characteristics of lignite with different oxidation temperatures under different ambient humidity were investigated by terahertz time-domain spectroscopy (THz-TDS), and the mechanism was analyzed by combining the synchronous thermal analyzer. Results indicate that the refractive index of lignite has abnormal dispersion characteristics. THz waves have different transmission characteristics in lignite with different oxidation temperatures, which is reflected in the amplitude difference of time-domain and frequency-domain signals. The complex refractive index of lignite shows obvious oxidation temperature dependence, which is closely related to the physicochemical changes that occur during coal oxidation. Besides, ambient humidity has a significant effect on the THz spectroscopy measurement, which follows the Beer-Lambert law. As humidity increases, the amplitude of time-domain and frequency-domain signals decays linearly, while the complex refractive index increase linearly. Humidity has a similar effect on coal samples with different oxidation temperatures, which means that based on linear effects and good fit results, THz spectroscopy measurements in humid environments can be corrected by a simple linear empirical formula. The results of this study are helpful to study the spectroscopy characteristics of coal in the THz band, and provide guidance for the application of terahertz technology in coal mines. [ABSTRACT FROM AUTHOR]

The causes of abnormal wear in contact strip of pantograph have been extensively investigated. Initially, based on field data analysis, the wear rate of strip was found to be strongly correlated with ambient humidity. Subsequently, a series tests of the strip was conducted, and the micromorphology was preformed post-tests, which indicated the evolution law of wear rate under different ambient humidity conditions. Finally, through grey relational analysis, it was observed that the degree of correlation between different influencing factors and wear rate at low humidity was greater than that at high humidity. Based on the findings of the aforementioned study, it is concluded that the abnormal wear of strip is caused by a decrease in ambient humidity. [ABSTRACT FROM AUTHOR]

Purpose: This study was initiated to assess the impact of outside environmental humidity on the refractive and visual outcome of laser-assisted in situ keratomileusis (LASIK) in myopic eyes. Materials and Methods: One thousand and fifty-two eyes of 1,052 consecutive myopic patients (419 males and 633 females; mean age at surgery 35.0 ± 9.0 years) with mean preoperative refractive spherical equivalent (SE) of −3.88 ± 1.85 diopters (D) were studied. Two subgroups were defined, which had undergone surgery either during meteorological winter or summer. Result: By 1-month (33.0 ± 5.0 days) follow-up, a mean postoperative SE of −0.18 ± 0.44 D was obtained. Bivariate comparison showed that statistically significant better safety index (SI) was obtained for high outside environmental humidity. Robust regression methods indicated high humidity to be associated with significant better SI and postoperative SE. No change of more than one line on logMar scale was obtained. Conclusion: Although being statistically significant, there is no clinically relevant difference in outcome of LASIK, which demonstrates its highly standardized quality. However, we observed a tendency that high outside environmental humidity at the day of LASIK and during early perioperative time, tends to produce better refractive outcome. Prospective, longitudinal studies are warranted to address meteorotropic reactions through evaluating individual risk profiles.

The effect of ambient humidity on the performance and pollutant emissions of internal combustion engines is not considered in the literature despite type-approval criteria are moving closer to real driving conditions. This work analyses experimentally the effects of charge air humidity at high warm altitudes, where the use of exhaust gas recirculation (EGR) is typically lowered and even avoided to recover engine performance at the expense of NOx emissions increase, on the response of a compression-ignition engine under a wide range of steady-state conditions in terms of engine-out emissions and specific fuel consumption. The impact of specific humidity variations within the atmospheric range was analysed by coupling the engine to an altitude simulator with pressure, temperature, and humidity control capabilities. High altitudes and warm & high ambient temperatures were explored (2000 m at 30 °C and 2500 m at 45 °C) to cover ambient specific humidity up to 30 g water /kg dry_air. In addition, the effects of increasing the specific humidity above the atmospheric levels were considered at 2500 m and 45 °C to emulate forced injection of water in the engine intake line corresponding to 60 g water /kg dry_air. With this approach, understanding of the role of humidity is provided to highlight its importance as additional ambient property in emission control. In parallel, the assessment of the forced water content increase to control NOx emissions when EGR must be lowered was performed due to the altitude impact on the engine performance and turbocharger limits. The results showed a consistent and significant reduction in engine-out NOx emissions as the ambient humidity increased, reaching up to 300% with respect to the dry case, caused by the decrease in O 2 availability due to the water content increase. The benefits of high humidity in NOx emission control at high altitudes when EGR is not feasible were complemented by an improved trade-off with particulate matter emission compared to the standard from EGR use. The results evidenced a reduction in opacity close to 250% for a given engine-out NOx emission when EGR was replaced by water content. By contrast, the slowdown of the combustion process as the fresh air humidity increased deteriorated the specific fuel consumption significantly as the engine load and speed increased. Nevertheless, these penalties ranged from 2 to 2.7% in the worst conditions and showed the same sensitivity for EGR and humidity increases. • Effect of humidity on CI engines demonstrated regardless of other ambient variables. • Altitude & humidity conditioning system to emulate Earth and forced water content. • Humidity reduces O 2 by dilution, volumetric efficiency, and gas constant penalties. • High water content reduces NOx and improves the trade-off with PM compared to EGR. • Forced water injection as a substitute and/or complement of EGR in altitude operation. [ABSTRACT FROM AUTHOR]

Black carbon (BC) and its mixing state were measured with a ground-based single particle soot photometer in urban Beijing during the extremely polluted winter of 2013. Up to 70 ± 14% of the BC-containing particles were thickly-coated during periods of haze, compared to 37 ± 9% on non-hazy days. The thickly-coated number fraction (NF BC-thick ) increased with increasing BC, reaching a plateau at ∼80–90% when BC concentrations were ≥15 μg m −3 and visibility was ≤2 km. Regional inflows brought more aged, highly thickly-coated BC to Beijing during haze. The absorption coefficient showed a distinct linear correlation with BC concentration; the mass absorption efficiency (MAE) of BC was acquired, with an overall mean of 4.2 ± 0.01 m 2 g −1 at 870 nm. The MAE of BC amplified with increasing ambient relative humidity. This was largely explained by the increase in NF BC-thick , which was likely due to the enhanced production of secondary aerosol under humid conditions. [ABSTRACT FROM AUTHOR]