Relationships of tensile strength with crosslink density for the high-carbon black-filled EPDM compounds with various softeners

Equilibrium swelling and rheological tests were adopted to systematically investigate the effects of softener type and dosage on the crosslink densities. The results turned out that the chemical crosslink density could be distinguished from the physical crosslink density by comparing the results of equilibrium swelling and rheological tests. The liquid butadiene (LB) as a softener leads to the greatest reduction in crosslink density, followed by polyethylene wax (PW) and paraffinic oil (PO). The tensile strength decreases with increasing PO content while shows peak values with increase of LB and PW contents. The dependencies of chemical crosslink density on the aging time under 150°C are quite different for the three softeners, which can be expected from the double crosslinking networks consisting of small softener and large main crosslinking networks. Further investigation has been performed to correlate the tensile strength with chemical crosslink density of ethylene propylene diene monomer elastomer vulcanizates. Three different linear relationships can be obtained for the softeners independent of the aging time. It can now be expected from this study that the role of some new softeners in rubber compounds is not only confined to plasticization but also forms crosslinking networks in the peroxide-cured rubbers.     

SIL验证与安全仪表系统的优化设计

安全仪表功能(SIF)回路是为了降低特定场景的安全风险而设置的,定级报告中SIF回路的功能描述是工艺设计的完整逻辑要求,包含关键动作及附件动作。安全完整性等级(SIL)验证属于概率学领域研究范畴,影响失效率的因素多且复杂。如果SIL验证无法通过,将造成大量的设计变更,浪费工程投资,影响工期。设计人员应关注SIL定级报告中关键动作的识别、要求平均失效概率以及SIF回路架构的约束。按照文中方法优化测量元件、逻辑控制器、执行元件及辅助元件的设计,可增加通过验证的概率。在没有预验证及安全要求规格书时,可以参考文中典型可通过SIL验证的SIF回路的经验架构进行优化设计,以减少工程变更。     

Omics Analysis of Blood-Responsive Regulon in Bordetella pertussis Identifies a Novel Essential T3SS Substrate

Bacterial pathogens sense specific cues associated with different host niches and integrate these signals to appropriately adjust the global gene expression. Bordetella pertussis is a Gram-negative, strictly human pathogen of the respiratory tract and the etiological agent of whooping cough (pertussis). Though B. pertussis does not cause invasive infections, previous results indicated that this reemerging pathogen responds to blood exposure. Here, omics RNA-seq and LC–MS/MS techniques were applied to determine the blood-responsive regulon of B. pertussis. These analyses revealed that direct contact with blood rewired global gene expression profiles in B. pertussis as the expression of almost 20% of all genes was significantly modulated. However, upon loss of contact with blood, the majority of blood-specific effects vanished, with the exception of several genes encoding the T3SS-secreted substrates. For the first time, the T3SS regulator BtrA was identified in culture supernatants of B. pertussis. Furthermore, proteomic analysis identified BP2259 protein as a novel secreted T3SS substrate, which is required for T3SS functionality. Collectively, presented data indicate that contact with blood represents an important cue for B. pertussis cells.     

超细粉在内循环流化床中的流态化特性

在内径120 mm的半圆柱形内循环流化床中,以平均粒径387 nm的Ti O2为原料,考察了单独通入流化气、射流气和同时通入流化气和射流气三种流化方式下超细粉的流化特性以及射流气速对超细粉聚团尺寸的影响。结果表明:同时通入流化气和射流气时,流化气能促进粉体循环,消除环隙死区;高速射流能有效破碎聚团,显著减小聚团尺寸,从而使超细粉在环隙区与导流管之间形成稳定循环,小聚团在环隙区实现平稳流态化。随着射流气速的增大,聚团尺寸减小,粒度分布变窄,在射流气速分别为60,90,120,150 m/s的条件下,聚团平均直径分别为194,158,147,135μm。     

简易棋盘格图像标定系统应用

棋盘格图像在摄像机标定中有非常广泛的应用,对于复杂环境且测量精度要求非常高的场合,会需要特定的且有一定复杂度的算法,但通常情况下,使用这样的标定系统是没有必要的,且会让初次应用的人觉得困难。这里提供一套应用简单,快速,对棋盘格图像具有旋转不变性,良好的鲁棒性,且对非复杂环境具有高精度的标定系统。所有算法均是在前辈们的算法上稍作改变而来,应用效果非常好。     

土壤冲击特性的实验研究

本文利用分离式Hopkinson压杆研究了土体在不同应变率条件下的冲击动态力学性能，发现土体有明显的应变率效应，与静载相比，冲击荷载下土的动强度和动模量均有很大的提高。     

循环水冷却塔风机软启动器应用及分析

本文分析了冷启动却塔风机直接启动方式对风机造成的一些危害。并对冷却循环水风机软启动器改造前、后作了比较 ,重点说明了如何利用软启动器在原冷却塔风机电机上实现限流启动以及改造后在实践过程中存在的一些问题 ,提出了改进措施。     

利用Hilbert-Huang变换提取地震信号瞬时参数

 通过Hilbert变换求取的信号瞬时参数并非对任何信号都有物理意义，此法通常要求被分析信号是窄带或平稳的，而且对噪声很敏感。而实际地震信号既非平稳又含有噪声，若在实际应用中不加考虑地对地震信号进行Hilbert变换以求取瞬时参数，这种情况下求取的瞬时参数将缺乏物理意义甚至失真。Hilbert-Huang变换是一种新的分析非平稳非线性信号的方法，它先将信号进行经验模态分解（EMD），形成有限个固有模态函数（IMF）之和，再对固有模态函数作Hilbert变换求取时频谱，求取的时频谱在时域和频域都具有较高的分辨率。本文将Hilbert-Huang变换应用于地震瞬时参数的提取，实例表明，对地震剖面做EMD可以得到不同时间尺度上的特征，Hilbert谱比传统的时频谱在时间和频率域上的分辨率都要高，强反射层在第1阶IMF瞬时频率剖面上比原瞬时频率剖面上表现得更为明显。