Effects of the number of benzene rings on the properties of single-source ZrC-based liquid precursors and nano zirconium carbide powders thereof

Effects of carbon source in single-source ZrC-based liquid precursors on the properties of the precursors and precursor-derived nano ZrC powders were investigated. The liquid precursors were prepared by directly blending and heating zirconium n-butoxide with either 2,4-pentanedione, benzoyl acetone or 1,3-diphenyl-1,3-propanedione additives which have the same chemical composition and structure except for the number of benzene rings (0, 1 and 2, respectively) in order to control the carbon content in the precursors. The ceramic yield of the precursor decreased as the number of benzene rings in the precursors increased. The stability of the precursors in air and the carbon content of the ceramic powder increased when using 1,3-diphenyl-1,3-propanedione additive. X-ray pure nano zirconium carbide powders with ultra-fine size (30 nm), isotropic shape and homogeneous particle size distribution were synthesized from the liquid precursors containing two benzene rings in the structure. Compared with ZrC powders derived from the precursors containing zero or one benzene ring, the powder from the precursor containing two benzene rings was finer and more homogeneous in size distribution.     

Analysis of color volume of multi‐chromatic displays using gamut rings

There are claims that multi‐chromatic displays can achieve a wider color gamut by the use of additional highly saturated secondary color channels. However, there are other claims that these displays lose lightness and/or color saturation at brighter levels. These apparently divergent views have led to some controversy in the display industry and at standard setting organizations. This study examines the color gamut volume for a variety of simulated and measured multi‐chromatic (sometimes incorrectly referred to as “multi‐primary”) displays using combinations of white and/or secondary color channels, such as cyan, magenta, and yellow. Furthermore, a two‐dimensional gamut representation, referred to as “gamut rings,” is introduced to illustrate that the addition of nonprimary optical color channels to a trichromatic (RGB) display can result in a significant decrease in the chroma at higher lightness levels. The additional saturated color channels can increase the gamut volume only around their hues at darker levels. The results also confirm the validity of comparing the color light output and white light output for revealing the design trade‐offs between the high‐peak white and the color‐image brightness for multi‐chromatic displays.     

旋转叶片电加热防冰系统设计与应用

在开展结冰试验时，结冰风洞风扇叶片前缘有结冰风险，影响风洞安全运行。针对大型旋转叶片结冰问题，提出了旋转叶片电加热防冰系统设计方法，研制了大型结冰风洞旋转叶片电加热防冰系统。首先，研制了内置电加热单元和温度反馈的防冰叶片。针对叶片复杂的工作环境，提出一种新的旋转叶片电加热防冰功率计算方法，通过精确测量和方案优化，设计了基于特殊环境的分半式、大尺寸、高线速度、碳刷自动移开/压紧的导电滑环。最后，采用变结构分级温度闭环和试验参数连锁防冰控制策略解决了旋转叶片结冰问题。该系统已应用于大型结冰风洞，运行中加热电流和叶片温度反馈信号传输连续，所有旋转叶片前缘快速加热且温度分布均匀，防冰效果好。     

Synthesis of ionic liquids based on alkylimidazolium salts and their coal dissolution and dispersion properties

A series of new bis (imidazolium) cation-based ionic liquids, wherein two imidazole rings are tethered by alkyl ether chains (oxygen numbers) of different lengths, were prepared, and their coal dissolution and dispersion properties were studied. It was found these ionic liquids can be used to fragment, disperse, and partially dissolve micrometer-size coal particles by simply mixing ionic liquid/coal dispersions. Dissolution performances and light hydrocarbon production were found to be sensitively increased by increasing the lengths of alkyl ether chains between imidazolium rings.     

连续斜支承梁的计算模式及受载特性分析

本文在充分考虑了连续斜支承梁的支承特性后,提出了连续斜支承梁的弹性支承计算图式,并以空间梁单元为基本工具对连续斜支承梁进行求解,这为连续斜支承梁的研究提供了另一条思路.文中最后给出一个算例,与刚性支承模式进行了比较,并对连续斜支承梁的影响因素进行了分析.     

不同压弯量对无缝钢管斜辊矫直残余应力分布的影响

从研究2-2-2型无缝钢管斜辊矫直机矫直过程入手,基于大变形弹塑性有限元法,应用ANSYS/LS-DYNA软件建立了Ф88 mm×10 mm×2500 mm无缝钢管斜辊冷矫直的数值模型。通过模拟计算分析不同压弯量对钢管矫直后残余应力分布状况的影响,并与X-Ray衍射结果对比。模拟结果表明:矫直后钢管轴向、环向残余应力的峰值均随压下量的增大而增大;钢管轴向残余应力内表面为压应力,外表面为拉应力;环向残余应力从内至外逐渐由压应力变为拉应力,且越靠近内、外表面残余应力值越大。模拟实验结果与真实结果吻合。     

一款高性能时钟驱动器电路的设计

时钟器件芯片可以实现通信网定时同步、时钟产生、时钟恢复和抖动滤除、频率合成和转换、时钟分发和驱动等功能。在系统设计中,选用好的时钟驱动芯片,可以省去系统时钟树设计,既节省空间,又提高系统性能。介绍一款高性能时钟驱动器的集成电路设计方法,主要性能要求有:低传播延时、低输出偏斜、低输出抖动、抗电磁干扰能力、抗ESD能力,一一详述了达到各项要求的设计。     

Construction of a polynomial invariant annihilation attack of degree 7 for T-310

Abstract

Cryptographic attacks are typically constructed by black-box methods and combinations of simpler properties, for example in [Generalised] Linear Cryptanalysis. In this article, we work with a more recent white-box algebraic-constructive methodology. Polynomial invariant attacks on a block cipher are constructed explicitly through the study of the space of Boolean polynomials which does not have a unique factorisation and solving the so-called Fundamental Equation (FE). Some recent invariant attacks are quite symmetric and exhibit some sort of clear structure, or work only when the Boolean function is degenerate. As a proof of concept, we construct an attack where a highly irregular product of seven polynomials is an invariant for any number of rounds for T-310 under certain conditions on the long term key and for any key and any IV. A key feature of our attack is that it works for any Boolean function which satisfies a specific annihilation property. We evaluate very precisely the probability that our attack works when the Boolean function is chosen uniformly at random.     

Study on spiral wall thickness unevenness of thin- walled tubes rolled by Assel rolling mill

In view of the internal thread defect of thin- walled tubes rolled by Assel 3- roll skew rolling mill, Assel cross- rolling process of X20Cr13 steel tube with typical specification of ??160mm??6. 5mm was numerically simulated by using 3D finite element analysis software Simufact. The influences of different mandrel movement modes, feeding angles and rolling strip profiles on the depth of internal thread were studied. The results show that the depth of the internal thread of steel tube rolled by the full floating mandrel is the most shallow, the second is that of the fixed mandrel and that of the pull mandrel is worst, and it will be gradually deepened when the feed angle increases; the hyperbolic rolling strip is more conducive to controlling the internal thread depth of the rolled tube. Under the condition of hyperbolic rolling strip, the amount of twist deformation of the rolled tube in the rolling process is about 35% smaller than that of the straight rolling strip.     

整体式桥台斜梁桥的设计与研究

整体式桥台桥梁作为一种新兴的桥梁结构形式,有许多优点,但受力性能十分复杂,给其推广应用带来了许多难题。文章探讨了整体式桥台斜梁桥设计及研究的重点和难点,介绍了桥长、斜交角的限制,以及简化计算思路,为整体式桥台斜梁桥的设计和研究提供一定的理论基础。