PROPERTIES OF ELECTROMAGNETIC SHIELDING CASE MADE OF PLYWOOD LAMINATED WITH CONDUCTIVE SHEETS

ABSTRACT Electromagnetic shielding cases have been regarded as an adequate solution for electromagnetic interference problems. Most electromagnetic shielding cases are made of metal, conductive plastics and carbon materials. Wood-based electromagnetic shielding cases have gained high levels of public interests due to their availability, cost, and renewability. In this study, the case was constructed of electromagnetic shielding plywood connected by copper foil. Shielding properties of the case were evaluated using shielded room testing. It was found that shielding effectiveness of the case ranged from 30.01 to 43.89 dB (30 MHz to 1 GHz), which indicated it met the secondary shielding effectiveness requirements of general cases for electronic equipment and could be used under the high requirements of electromagnetic compatibility. The results also showed seam leakage between the sides of cases resulted in a decrease of electromagnetic shielding effectiveness. The longer the seam length, the lower the shielding performance was. In addition, it was observed that rectangular waveguide resonance had an obvious influence on the case, which led to a sharp decrease of shielding effectiveness at the frequency of 720 MHz

BnaMPK3 Is a Key Regulator of Defense Responses to the Devastating Plant Pathogen Sclerotinia sclerotiorum in Oilseed Rape

The disease caused by Sclerotinia sclerotiorum has traditionally been difficult to control, resulting in tremendous economic losses in oilseed rape (Brassica napus). Identification of important genes in the defense responses is critical for molecular breeding, an important strategy for controlling the disease. Here, we report that a B. napus mitogen-activated protein kinase gene, BnaMPK3, plays an important role in the defense against S. sclerotiorum in oilseed rape. BnaMPK3 is highly expressed in the stems, flowers and leaves, and its product is localized in the nucleus. Furthermore, BnaMPK3 is highly responsive to infection by S. sclerotiorum and treatment with jasmonic acid (JA) or the biosynthesis precursor of ethylene (ET), but not to treatment with salicylic acid (SA) or abscisic acid. Moreover, overexpression (OE) of BnaMPK3 in B. napus and Nicotiana benthamiana results in significantly enhanced resistance to S. sclerotiorum, whereas resistance is diminished in RNAi transgenic plants. After S. sclerotiorum infection, defense responses associated with ET, JA, and SA signaling are intensified in the BnaMPK3-OE plants but weakened in the BnaMPK3-RNAi plants when compared to those in the wild type plants; by contrast the level of both H2O2 accumulation and cell death exhibits a reverse pattern. The candidate gene association analyses show that the BnaMPK3-encoding BnaA06g18440D locus is a cause of variation in the resistance to S. sclerotiorum in natural B. napus population. These results suggest that BnaMPK3 is a key regulator of multiple defense responses to S. sclerotiorum, which may guide the resistance improvement of oilseed rape and related economic crops

A deep learning-based prognostic framework for aeroengine exhaust gas temperature margin

The value of the gas-path parameter, exhaust gas temperature margin (EGTM), is the critical index for predicting aeroengine performance degradation. Accurate predictions help to improve engine maintenance, replacement schedules, and flight safety. The outside air temperature (OAT), altitude of the airport, the number of flight cycles, and water washing information were chosen as the sample input variables for the data-driven prognostic model for predicting the take-off EGTM of the on-wing engine. An attention-based deep learning framework was proposed for the aeroengine performance prediction model. Specifically, the multiscale convolutional neural network (CNN) structure is designed to initially learn sequential features from raw input data. Subsequently, the long short-term memory (LSTM) structure is employed to further extract the features processed by the multiscale CNN structure. Furthermore, the proposed attention mechanism is adopted to learn the influence of features and time steps, assigning different weights according to their importance. The actual operation data of the aeroengine are used to conduct experiments, where the experimental results verify the effectiveness of our proposed method in EGTM prediction

Estimation of Land Surface Temperature Over the Tibetan Plateau Based on Sentinel-3 SLSTR Data

Land surface temperature (LST) plays a crucial role in the energy and water cycles of the Earth's climate system. The uncertainty of LST retrieval from satellites is a fundamental and long-standing issue, especially in plateau areas [such as the Tibetan Plateau (TP)], due to its high altitude, unique hydrometeorological conditions, and complex underlying surfaces. To improve the accuracy of LST retrieval over the TP, different methods, including the single channel (SC) algorithm, the split-window (SW) algorithm, and four machine learning (ML) models, were used to retrieve the LST based on sea and land surface temperature radiometer (SLSTR) data in this study. The validation results indicated that the root-mean-square errors (RMSEs) of the LSTs retrieved by the SC and SW algorithms were 3.48 and 2.64 K, respectively, which shows a better performance than the official SLSTR LST products (5.23 K). In addition, the random forest model has the highest accuracy among the four ML models, with an RMSE of 3.26 K. By comparing the performance of various methods, the SW algorithm is more stable and reliable for LST retrieval over the TP. In addition, the accurate spatiotemporal distribution of the LST based on the SW algorithm was also analyzed, which would benefit the understanding of the physical processes of energy and water cycles over the TP

Experimental and modeling investigation on compression springback property of mullite fiber reinforced silica aerogel composites

Uniaxial compression tests were carried out on mullite fiber reinforced silica aerogel composites in the out-of-plane direction. Influences of different ultimate strains and thermal exposure temperatures on the compression springback behavior and deformation recovery capability were investigated. Internal mechanisms based on the microstructure morphology changes were explained. Phenomenological mechanical models were established respectively for the deformation behavior in the loading and unloading stages. The results show that the compression springback behavior of mullite fiber reinforced silica aerogel composites exhibits nonlinear characteristics. The greater the ultimate strain, the worse the deformation recovery capability. High temperature thermal exposure pre-treatment has an effect on the compression springback property, the higher the thermal exposure temperature, the worse the deformation recovery capability. The aggregation of matrix particle-cluster structure and the formation and collapse of the large size holes are main causes. The phenomenological mechanical model can be used to describe the stress-strain curve of the composites during loading and unloading. The fitting results are in good agreement with the experimental data

Unique organizational and functional features of the cytochrome c maturation system in Shewanella oneidensis.

Shewanella are renowned for their ability to respire on a wide range of electron acceptors, which has been partially accredited to the presence of a large number of the c-type cytochromes. In the model species S. oneidensis MR-1, at least 41 genes encode c-type cytochromes that are predicted to be intact, thereby likely functional. Previously, in-frame deletion mutants for 36 of these genes were obtained and characterized. In this study, first we completed the construction of an entire set of c-type cytochrome mutants utilizing a newly developed att-based mutagenesis approach, which is more effective and efficient than the approach used previously by circumventing the conventional cloning. Second, we investigated the cytochrome c maturation (Ccm) system in S. oneidensis. There are two loci predicted to encode components of the Ccm system, SO0259-SO0269 and SO0476-SO0478. The former is proven essential for cytochrome c maturation whereas the latter is dispensable. Unlike the single operon organization observed in other γ-proteobacteria, genes at the SO0259-SO0269 locus are uniquely organized into four operons, ccmABCDE, scyA, SO0265, and ccmFGH-SO0269. Functional analysis revealed that the SO0265 gene rather than the scyA and SO0269 genes are relevant to cytochrome c maturation

Remote sensing of land surface parameters in the middle reaches of Yarlung Zangbo River and its two tributaries from AVHRR and MODIS data

The middle reaches of Yarlung Zangbo River (YR) and its two tributaries is a region in central Tibet Autonomous Region where the industrial and agricultural economy is most concentrative and developed. Remote sensing of land surface parameters has significant meaning for crop growth monitoring, crop yield assessment and disaster monitoring. It also has great theoretical importance for understanding energy and water cycle in local area and even for surrounding regions. In this paper, four scenes data in 2003 under nearly clear weather conditions are selected as the spring, summer, autumn and winter cases. Different algorithms for AVHRR and MODIS data will be applied to retrieve land surface temperature (LST), albedo, Normalized Difference Vegetation Index (NDVI), vegetation coverage, emissivity, and water vapour content, respectively. The derived LST, albedo are validated with field measurements and MODIS products. The estimations are in good agreement with in-situ measurements, with MODIS retrievals being slightly better than those of AVHRR. This means that the adopted remote sensing retrieval algorithms are not only applicable but also simple for the study area. As called the "water vapour inflow corridor", the valleys of YR and its two tributaries are proved to have higher LST and larger atmospheric water vapour content. Spatiotemporal variations of land surface parameters in the middle reaches of YR and its two tributaries can also be clearly identified

Dominant Modes of Tibetan Plateau Summer Surface Sensible Heating and Associated Atmospheric Circulation Anomalies

Based on empirical orthogonal function (EOF) analysis, the dominant modes of variations in summer surface sensible heating (SH) over the Tibetan Plateau (TP), as well as the associated atmospheric circulation anomalies, were investigated in this study. The results show that the first dominant mode of summer SH presents a feature of decadal reduction over the whole TP on an interdecadal time scale, and the second dominant mode is characterized by a zonally asymmetric pattern with positive (negative) SH anomalies in the western (eastern) TP on an interannual time scale. The variations of summer SH are dominated by anomalies in downwelling surface shortwave radiation (DSWR), which are associated with atmospheric circulation changes. The first dominant mode of variation in SH is connected to the interdecadal variation of the Silk Road Pattern (SRP). Further analysis reveals that the interdecadal phase shift of the SRP induces anticyclone circulation to the northeast of the TP, leading to enhanced water vapor supply and convergence over the TP. This can lead to an increase in the total cloud cover, and a reduction in DSWR, contributing to the decadal reduction in SH over the TP. The second dominant mode of variation in SH is related to a stationary teleconnection pattern over the Eurasian continent named the North Atlantic-East and North Asia pattern (NAENA). Corresponding to the positive phase of the NAENA, there is a cyclone anomaly to the west TP, leading to anomalous water vapor convergence (divergence) over the eastern (western) TP. This can result in enhanced (decreased) cloud cover, reduced (increased) DSWR, and therefore, an anomalous decrease (enhancement) in SH over the east (west) of the TP. Furthermore, the southwesterly wind anomaly, which is accompanied by the anomalous cyclone to the west TP, leads to positive SH in the western TP