Broadband absorption of macro pyramid structure based flame retardant absorbers

Flame-retardant materials with good electromagnetic wave absorption play an increasingly important role in Over-the-Air(OTA)tests in microwave anechoic chambers.In this work,carbon nanotubes and ammonium polyphosphate(CNTs@APP)composite were prepared by crosslinking with the silane coupling agent(KH550).The flame retardancy is improved with the increase of APP.However,the microwave absorption performance(MAP)and processing difficulty changed greatly as well.Therefore,magnesium aluminum double-layer metal hydroxide(LDH)was obtained by coprecipitation method and processing into the coating,so as to realize flame retardancy which reaches the limiting oxygen index(LOI)of 24.8%and good MAP at the same time.Then,a high-frequency structure simulator(HFSS^(TM))was used to simulate the pyramid model to realize the broadband absorption,and the optimal parameter range was obtained,that is,when the total height of the material is 40 mm,the height of the base accounts for 1/5-1/3,and the tangent of the half top angle is near 1/5,which result in the best MAP.Finally,the broadband absorption of 14.36 GHz(3.64-18 GHz)was realized when the base height is 1/3,and the broadband absorption of 14 GHz(4-18 GHz)can be realized under the condition of large-angle oblique incidence of 0°-60°.

Pyramidal Structure of Chinese Publicly-Listed Private Firms:Motivations, Correlations and Paths to Governance

It is generally believed in academia that there are two theoretical explanations of tunneling and financing advantage for the creation of pyramidal structure. However, there is no definitive conclusion on which explanation holds sway. Based on non-equilibrium panel data of seven years between 2004 and 2010, this empirical study uses the product market competition variables of ＂inter-sector competition＂ and ＂intra-sector competition＂ and the hierarchy and complexity of pyramidal structure, examines the correlation between pyramidal structure of Chinese private manufacturing listed firms and product market competition and patterns of change, and reveals the major causes of pyramidal structure. Empirical result indicates that, for Chinese private manufacturing listed companies, there is a significant negative correlation between product market competition and the hierarchy and complexity of pyramidal structure, which indicates that the creation of pyramidal structure has a preference on tunneling by controlling shareholders. On the basis of further considerations on corporate tunneling and financing restraint categorization, high-tunneling firms and firms with low financing restraint demonstrate significant tunneling motivations; low-tunneling firms and firms with high financing restraint demonstrate significant effect of financing advantage, which further testifies both theoretical explanations for the creation of pyramidal structure. Conclusions of these studies have not only enriched and supplemented relevant studies on the root causes for the creation of pyramidal structure by Chinese private business groups, but provide practical support for firms to make correct and effective use of pyramidal structure as well.

Infrared Absorption and [CuO_5] Pyramid of High T_c Superconductor Bi-Sb-Sr-Ca-Cu-O System

The infrared absorption spectra of different superconducting phase of high Tc super conductor Bi-Sb-Sr-Ca-Cu-O have been measured . The results show that only in the range of 400cm-1 -700cm-1,there is a group of peaks which changes with different superconducting phases.According to group theory and infrared spectra of CuO, this group of peaks could be assigned to be the [CuO6]octahedron, the [CuO5] pyramid and the [CuO4]plane quadrilateral,but not CU-O plane or CU-O chain. Furthermore, the quasi-three dimensional Cu-O layers consisting of [CuO5] pyramids and proper coupling between them are essential factor for high Tc. It seems that the weaker compling of layers, the higher Tc

Investigations on Structured Polyamide for Laser Sintered Body Armor

Stab resistance body armor（SRBA）is essential in protecting people from knife injuries.The protective parts of traditional SRBA are made of multi-layered ultra-high molecular weight polyethylene（UHMWPE）,which causes heavy heat stress for people wearing it.The protective parts of SRBA manufactured using laser sintering（LS）3D printing technology provide high manufacturing flexibility and low weight.Two different structures,plain plate and pyramid-structured plate,were investigated.The pyramid structure showed much higher stab resistance property then the plain plate,because of the angle and thickness effects.This is the first effort applying the LS technology and polyamide（PA）material（PA3200）on SRBA.By applying the pyramid structure on the protective layer of the SRBA,the total weight could reduce 30%-40%.

Effect of temperature on the compressive behavior of carbon fiber composite pyramidal truss cores sandwich panels with reinforced frames

This paper focuses on the effect of temperature on the out-of-plane compressive properties and failure mechanism of carbon fiber/epoxy composite pyramidal truss cores sandwich panels （CF/CPTSP）. CFJCPTSP with novel reinforced frames are manufactured by the water jet cutting and interlocking assembly method in this paper. The theoretical analysis is presented to predict the out-of-plane compressive stiffness and strength of CFJCPTSP at different ambient temperatures. The tests of composite sandwich panels are per- formed throughout the temperature range from -90℃ to 180℃. Good agreement is found between theo- retical predictions and experimental measurements. Experimental results indicate that the low tempera- ture increases the compressive stiffness and strength of CF/CPTSP. However, the high temperature causes the degradation of the compressive stiffness and strength. Meanwhile, the effects of temperature on the failure mode of composite sandwich panels are also observed.

Pyramidal Edge Detection Method Based on AWFM Filtering and Fuzzy Linking Model

A novel multiresolution pyramidal edge detector, based on adaptive weighted fuzzy mean(AWFM)filtering and fuzzy linking model, is presented in this paper. The algorithm first constructs a pyramidal structure by repetitive AWFM filtering and subsampling of original image. Then it utilizes multiple heuristic linking criteria between the edge nodes of two adjacent levels and considers the linkage as a fuzzy model, which is trained offline. Through this fuzzy linking model, the boundaries detected at coarse resolution are propagated and refined to the bottom level from the coarse-to fine edge detection. The validation experiment results demonstrate that the proposed approach has superior performance compared with standard fixed resolution detector andprevious multiresolution approach, especially in impulse noise environment.

Pyramid-VAE-GAN:Transferring hierarchical latent variables for image inpainting

Significant progress has been made in image inpainting methods in recent years.However,they are incapable of producing inpainting results with reasonable structures,rich detail,and sharpness at the same time.In this paper,we propose the Pyramid-VAE-GAN network for image inpainting to address this limitation.Our network is built on a variational autoencoder(VAE)backbone that encodes high-level latent variables to represent complicated high-dimensional prior distributions of images.The prior assists in reconstructing reasonable structures when inpainting.We also adopt a pyramid structure in our model to maintain rich detail in low-level latent variables.To avoid the usual incompatibility of requiring both reasonable structures and rich detail,we propose a novel cross-layer latent variable transfer module.This transfers information about long-range structures contained in high-level latent variables to low-level latent variables representing more detailed information.We further use adversarial training to select the most reasonable results and to improve the sharpness of the images.Extensive experimental results on multiple datasets demonstrate the superiority of our method.Our code is available at https://github.com/thy960112/Pyramid-VAE-GAN.