Storage Life Prediction of Rubber Products Based on Step Stress Accelerated Aging and Intelligent Algorithm

Compared with the constant stress accelerated aging test, the step stress accelerated aging test reduces the accelerated aging test time by increasing the aging temperature step by step to obtain the aging failure life of rubber in a shorter time, but its data processing method is not mature enough. In this paper, a simplified step is proposed to process the step stress accelerated aging data. The identification of the acceleration factor is transformed into an optimization problem to avoid the error accumulation problem caused by fitting the data at each temperature. Considering the non-Arrhenius phenomenon in the rubber aging process, a modified Arrhenius equation was used to extrapolate the acceleration factor at low temperatures to calculate the prediction curves for the degradation of polyurethane rubber properties at low temperatures. The life prediction results of the constant stress accelerated aging test and step stress accelerated aging test were compared, and the dispersion coefficient between the two results was between 0.9 and 1. The results obtained by the two methods were in good agreement, which proved the correctness and feasibility of the method used in this paper

Natural Aging Life Prediction of Rubber Products Using Artificial Bee Colony Algorithm to Identify Acceleration Factor

We aim to predict the natural aging life of 8016 ethylene propylene rubber accurately and quickly. Based on the time-temperature equivalent superposition principle, the artificial bee colony algorithm was introduced to calculate the acceleration factor of the accelerated aging test, and the calculation of the acceleration factor was considered an optimization problem, which avoided the error superposition problem caused by data fitting at each temperature. Based on the traditional Arrhenius equation, a power exponential factor was introduced to consider the non-Arrhenius phenomenon during the rubber aging process. Finally, the aging prediction curve of 8106 ethylene propylene rubber at 25 °C was obtained. The prediction results show that the artificial bee colony algorithm can quickly and accurately identify the acceleration factor of the accelerated aging test. The dispersion coefficients between the predicted and measured results of the improved and traditional Arrhenius equations are 1.0351 and 1.6653, respectively, which indicates that the improved Arrhenius equation is more advantageous in predicting the long-term aging process of rubber products

A Kalman Filter-Based Method for Reconstructing GMS-5 Land Surface Temperature Time Series

Satellite-derived environmental parameters play important roles in environmental research on global changes and regional resources. Atmosphere effects and sensor limitations often lead to data products that vary in quality. The main goal of time series data reconstruction is to use various statistical and numerical analysis methods and to stimulate changing seasonal or annual parameters, providing more complete data sets for correlational research. This paper aims to develop a time series reconstruction algorithm for LST based on data assimilation according to the current problems of unstable precision and unsatisfactory results, and the simplistic effects of evaluation methods while using remote sensing-derived LST data as the basic parameters and the daily LST data derived from the static meteorological satellite GMS-5 as the input data. The data assimilation system used the Kalman filter as the assimilation algorithm. A complete set of global refined LST time series data sets were obtained by constantly correcting the LST values according to the regional ground-based observations. This method was implemented using MATLAB software (version R2017a), and was applied and validated through partitioning using the principal elevation in the Beijing, Tianjin, and Hebei regions. The results show that the accuracy of the reconstructed LST data series improved significantly in terms of the mean and standard deviation. Better consistency was achieved between the variables obtained over a year from the reconstructed LST data and the ground observations from the LST data set

Microbial Community Analyses of the Deteriorated Storeroom Objects in the Tianjin Museum Using Culture-Independent and Culture-Dependent Approaches

In the storeroom C7 of the Tianjin Museum, one wooden desk and two leather luggages dated back to Qing dynasty (1644-1912 AD) presented viable microbial contamination. The aim of the present study was to investigate microbial communities responsible for the biodeterioration of storeroom objects using a combination of culture-independent and culture-dependent methods as well microscopic techniques. Scanning electron microscopy (SEM) revealed that the microflora on three storeroom objects were characterized by a marked presence of Eurotium halophilicum. Real-time quantitative polymerase chain reaction (qPCR) analysis proved that fungi were the main causative agents behind the biodeterioration in this case. Fungal internal transcribed spacer (ITS) amplicon sequencing documented the presence of two main fungi — Eurotium halophilicum and Aspergillus penicillioides. Molecular identification of fungal strains isolated from the surfaces and the air of the storeroom were most closely related to Chaetomium, Aspergillus, Penicillium, and Fusarium, showing discrepancies in fungal taxa compared to ITS amplicon sequencing. The most isolated bacterial phylum was Firmicutes, mostly Bacillus members. In addition, four biocide products — Preventol® D 7, P 91, 20 N and Euxyl® K 100 were selected to test their capability against fungal strains isolated from the surfaces. According to the susceptibility assay, Preventol® D 7 based on isothiazolinones was the most effective against fungal isolates. Findings from this study provided a knowledge about storeroom fungi, and exemplify a type of preliminary test that may be conducted before planning any biocide treatment, which may be useful to mitigate the fungal deterioration for further conservation of the museum

Design and Preparation of Flexible Graphene/Nonwoven Composites with Simultaneous Broadband Absorption and Stable Properties

As the world moves into the 21st century, the complex electromagnetic wave environment is receiving widespread attention due to its impact on human health, suggesting the critical importance of wearable absorbing materials. In this paper, graphene nonwoven (RGO/NW) composites were prepared by diffusely distributing graphene sheets in a polypropylene three-dimensional framework through Hummers’ method. Moreover, based on the Jaumann structural material design concept, the RGO/NW composite was designed as a multilayer microwave absorber, with self-recovery capability. It achieves effective absorption (reflection loss of −10 dB) in the 2~18 GHz electromagnetic wave frequency domain, exhibiting a larger bandwidth than that reported in the literature for absorbers of equivalent thickness. In addition, the rationally designed three-layer sample has an electromagnetic wave absorption of over 97% (reflection loss of −15 dB) of the bandwidth over 14 GHz. In addition, due to the physical and chemical stability of graphene and the deformation recovery ability of nonwoven fabric, the absorber also shows good deformation recovery ability and stable absorption performance. This broadband absorption and extreme environmental adaptability make this flexible absorber promising for various applications, especially for personnel wearable devices

Study on the Acousto-Optic Coupling Effect of a One-Dimensional Hetero-Optomechanical Crystal Nanobeam Resonator

The optomechanical crystal nanobeam resonator has attracted the attention of researchers due to its high optomechanical coupling rate and small modal volume. In this study, we propose a high-optomechanical-coupling-rate heterostructure with a gradient cavity, and the optomechanical rates of the single mirror and hetero-optomechanical crystal nanobeam resonators are calculated. The results demonstrate that the heterostructure based on the utilization of two mirror regions realizes better confinement of the optical and mechanical modes. In addition, the mechanical breathing mode at 9.75 GHz and optical mode with a working wavelength of 1.17 μm are demonstrated with an optomechanical coupling rate g0 = 3.81 MHz between them, and the mechanical quality factor is increased to 3.18 × 106

Design and Preparation of Flexible Graphene/Nonwoven Composites with Simultaneous Broadband Absorption and Stable Properties

As the world moves into the 21st century, the complex electromagnetic wave environment is receiving widespread attention due to its impact on human health, suggesting the critical importance of wearable absorbing materials. In this paper, graphene nonwoven (RGO/NW) composites were prepared by diffusely distributing graphene sheets in a polypropylene three-dimensional framework through Hummers’ method. Moreover, based on the Jaumann structural material design concept, the RGO/NW composite was designed as a multilayer microwave absorber, with self-recovery capability. It achieves effective absorption (reflection loss of −10 dB) in the 2~18 GHz electromagnetic wave frequency domain, exhibiting a larger bandwidth than that reported in the literature for absorbers of equivalent thickness. In addition, the rationally designed three-layer sample has an electromagnetic wave absorption of over 97% (reflection loss of −15 dB) of the bandwidth over 14 GHz. In addition, due to the physical and chemical stability of graphene and the deformation recovery ability of nonwoven fabric, the absorber also shows good deformation recovery ability and stable absorption performance. This broadband absorption and extreme environmental adaptability make this flexible absorber promising for various applications, especially for personnel wearable devices

Absorbing property of MnO2 nanorods and its meta-surface design

MnO2 nanorods were prepared by using the hydrothermal method and freeze-drying technology, and then molded into the MnO2/paraffin circular samples in different filling concentrations. The crystalline phase, microstructure and electromagnetic parameters of the samples were characterized and tested by X-ray diffractometer (XRD), scanning electron microscopy (SEM), and vector network analyzer (VNA). Sample meta-surface was designed and simulated by CST software and the pre and post simulation calculation and research of the meta-surface were carried out. The results show that prepared MnO2 powder has a rod structure with the diameter and length of the rod about 50-100 nm, 5-10 μm, respectively. The single cylindric structure is well-shaped, and the overall structure is homogeneous with crystallinity. Moreover, the tangent of dielectric loss(tanδ) increases with concentration, making a great contribution to the electromagnetic attenuation coefficient (α) of the sample of MnO2/paraffin, which increases with filling concentration of MnO2 nanorods. Microwave absorption frequency domain of MnO2/paraffin material is significantly broadened by the design of meta-surface, namely, the optimal bandwidth in 2-18 GHz can reach 14.32 GHz. The reason is the superposition of absorption peaks over a specified frequency range, which is caused by the coexistence of multiple resonances of the meta-surface