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31.
Rubber composites with very high moduli at low elongation, high elongation at break and high ultimate breaking strength have been developed. The matrix was acrylonitrile butadiene rubber (NBR) and the hybrid (fibrous and particulate) reinforcements were short, fine pineapple leaf fiber (PALF) and carbon black. The amount of PALF was fixed at 10 parts (by weight) per hundred of rubber (phr) while that of carbon black was varied from 0 to 30 phr. Uniaxial NBR composites were prepared. Tensile strength, elongation at break, modulus and tear strength of the hybrid composites were characterized in both longitudinal (parallel to the fiber axis) and transverse (perpendicular to the fiber axis) directions. The addition of carbon black causes the slope of the early part of the stress–strain curve to increase and also extends breaking to greater strains. At carbon black contents of 20 phr and above, the stress–strain relation displays an upturn at high elongations, providing greater ultimate strength. Comparison with the usual carbon black filled rubber shows that the composite behavior at low strains is determined by the PALF, and at high strains by the carbon black. This high performance PALF-carbon black reinforced NBR shows great promise for engineering applications. 相似文献
32.
Hyperbranched Hybridization Chain Reaction for Triggered Signal Amplification and Concatenated Logic Circuits 下载免费PDF全文
Dr. Sai Bi Min Chen Xiaoqiang Jia Ying Dong Prof. Dr. Zonghua Wang 《Angewandte Chemie (International ed. in English)》2015,54(28):8144-8148
A hyper‐branched hybridization chain reaction (HB‐HCR) is presented herein, which consists of only six species that can metastably coexist until the introduction of an initiator DNA to trigger a cascade of hybridization events, leading to the self‐sustained assembly of hyper‐branched and nicked double‐stranded DNA structures. The system can readily achieve ultrasensitive detection of target DNA. Moreover, the HB‐HCR principle is successfully applied to construct three‐input concatenated logic circuits with excellent specificity and extended to design a security‐mimicking keypad lock system. Significantly, the HB‐HCR‐based keypad lock can alarm immediately if the “password” is incorrect. Overall, the proposed HB‐HCR with high amplification efficiency is simple, homogeneous, fast, robust, and low‐cost, and holds great promise in the development of biosensing, in the programmable assembly of DNA architectures, and in molecular logic operations. 相似文献
33.
This paper mainly studies the problem of designing a hybrid state feedback D-admissible controller for a class of linear and nonlinear singular systems. Based on the relationship between singular discrete systems and singular delta operator systems, several necessary and sufficient conditions for a linear singular delta operator system to be D-admissible (i.e. regular, causal and all finite poles lie in a prescribed circular region) with different representations are derived. Then, the existence conditions and explicit expressions of a desirable D-admissible controller are given by means of matrix inequalities and strict linear matrix inequalities, respectively. We further extend the obtained results to singular delta operator systems with Lipschitz nonlinear perturbations, and the design methods of hybrid controller are presented for the nonlinear case as well. Finally, numerical examples as well as simulations are provided to illustrate the effectiveness of the theoretical outcomes obtained in the paper. 相似文献
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35.
IntroductionSincethespecialsuperiorityofartificialneuralnetworkstechnologyinvariousengineeringtechniquesfields,suchasoptimization ,associativememories,patternrecognition ,signalprocessingandautomaticcontrol,therehasbeenincreasinginterestintheinvestigati… 相似文献
36.
Xuqiang Ji Niu Yusheng Xu Yuanhong 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2019,93(6):1128-1132
Russian Journal of Physical Chemistry A - The design and development of excellent microwave absorption (MA) material is significant for healthcare, electronic, and security industries. Herein, a... 相似文献
37.
《中国化学快报》2020,31(8):2155-2158
Detection of trace-level hydrogen sulfide (H2S) gas is of great importance whether in industrial production or disease diagnosis. This research presents a novel H2S gas sensor based on integrated resonant dual-microcantilevers which can identify and detect trace-level H2S in real-time. The sensor consists of two integrated resonant microcantilever sensors with different functions. One cantilever sensor can identify H2S by outputting positive frequency shift signals, while the other cantilever sensor will detect H2S as a normally used cantilever sensor with negative frequency shifts. Combined the two cantilever sensors, the proposed gas sensor can distinguish H2S from a variety of common gases, and the detection limit to H2S of the sensor is as sensitive as below 1 ppb. 相似文献
38.
为获得攒尖四坡屋面的风致雪漂移规律,基于欧拉-欧拉方法和风雪单向耦合假定,运用计算流体动力学软件,选取Mixture模型分别对立方体周边和高低屋面上的风致雪漂移运动进行数值模拟,将模拟结果与两者的实地观测数据对比,探讨分析数值风洞的关键技术和参数设置,验证数值模拟方法的合理性与可靠性。依据攒尖四坡房屋的使用功能要求,设计分析模型与分析工况,在试算的基础上对屋面进行分区。以风速5 m/s,7 m/s,9 m/s,11 m/s,13 m/s和15 m/s,风向角0°,15°,30°和45°以及屋面坡度25°,30°,34°,40°和45°为分析参数,对攒尖四坡房屋的120种工况进行数值模拟,得到屋面各分区侵蚀沉积的基本规律,提出可用于抗雪设计的屋面积雪分布系数。研究表明,风向角的改变会使屋面积雪分布状态发生较大程度的变化,风速和屋面坡度的变化对屋面整体积雪量有较大影响。 相似文献
39.
The mooring loads on an aquaculture net cage in current and waves are investigated by dedicated model tests and numerical simulations. The main purpose is to investigate which physical effects are dominant for mooring loads, and in this respect, to investigate the validity of different rational hydrodynamic load models. Also structural and numerical aspects are investigated. The model tests are performed to provide benchmark data, while the numerical model is used to study the effect and sensitivity of different load models and parameters.Compared to a realistic aquaculture plant, the total system is simplified to reduce the complexity. The system does, however, include all the four main components of an aquaculture plant: net cage, floater, sinker weights and moorings. The net cage is bottomless, flexible and circular. It is attached to a circular, elastic floater at the top and has 16 sinker weights at the bottom. The system is nearly linearly moored with four crow feet mooring lines.The loads are measured in the four mooring lines. A systematic variation of current only, wave only as well as combined current and wave conditions is carried out. The numerical simulation results are first benchmarked towards the experimental data. The mean loads in general dominate over the dynamic part of the loads in combined current and waves, and they significantly increase in long and steep waves, relative to current only. Next, a sensitivity study is carried out. A rigid floater significantly alters the loads in the mooring lines compared to a realistic, elastic floater. The theoretical model for the wave matters. The mooring loads are rather insensitive to a majority of the parameters and models, in particular: frequency dependent added mass of the floater and nonlinear restoring loads. It seems not to be necessary to represent the net cage with a very fine numerical mesh. 相似文献
40.
Chang Mingning Wang He Zheng Yonglei Li Ningning Chen Siheng Wan Yong Yuan Feng Shao Weiquan Xu Sheng 《Journal of Solid State Electrochemistry》2019,23(2):607-613
Journal of Solid State Electrochemistry - Li1.2Ni1/3Co1/3Mn1/3O2 was synthesized as a cathode material for lithium-ion batteries and coated with various amounts of CoAl2O4 (0–5 wt%)... 相似文献