钢结构防火涂料对电缆保护效果的数值计算分析

钢结构防火涂料在电缆工程中,可用于对明敷穿管电缆的防火保护,但防火涂料的种类和厚度与保护效果之间没有明确的规律和依据可循。文章在实验研究的基础上,运用传热学理论建立了电缆穿涂敷钢结构防火涂料后在火灾条件下的内部温度分布模型,并采用MATLAB软件求得了模型的数值解,并据此获得电缆绝缘失效时间。对电缆在90种不同保护条件下的绝缘失效时间进行了计算,并对计算结果进行拟合,得到失效时间与防火涂料涂层膨胀厚度及热扩散系数之间的函数关系式,可为电缆防火设计、施工时确定涂料选型及涂刷厚度等参数的定量参考依据。     

In situ synthesis of ZrB2–MoSi2 platelet composites: Reactive hot pressing process,microstructure and mechanical properties

Using elemental Zr, B, Mo and Si as raw materials, partially textured ZrB₂–MoSi₂ composites with in situ platelet ZrB₂ grains were fabricated by reactive hot pressing. Synthesized by a combustion reaction, the in situ formed ZrB₂ phase had unique characteristics to grow up to platelet grains, on the surroundings of Mo–Si–B ternary liquid phase at high temperature. Mechanical properties were dependent on grain size and aspect ratio of the ZrB₂ platelets. The rotation and realignment of the platelet ZrB₂ grains under hot pressing led to a partially textured microstructure, which showed anisotropic mechanical properties on different directions of the as-sintered samples. A roadmap of the reaction process, microstructure evolution and texture formation was given to describe the preparation of partially textured ZrB₂–MoSi₂ composites by reactive hot pressing.     

Experimental investigation on the piezo-composite actuator with piezoelectric single-crystal layer

Studies on muscle mimicking actuators have increased in the last two decades due to the possibility of various applications for compact lightweight actuators including small unmanned aircrafts, missile, and biomimetic robots. Piezoelectric materials have been used in a variety of applications ranging from shape control of structure and active vibration control of structure to noise suppression due to compact size and good frequency response. Conventional polycrystal piezoelectric ceramic materials, however, have limited actuating strains and displacement, hindering their use in actuators for small aerospace vehicles. In this study, the design and fabrication method of an actuator with a piezoelectric single-crystal layer were investigated to increase the actuation strain and displacement. From a comparison of the performance of the LIPCA-C2 and LIPCA-S prototypes, it was found that the new LIPCA-S2, which has much higher coefficient of the unimorph actuator, can generate an actuating displacement more than twice that of LIPCA-C2.     

Mechanism of Macrosegregation Formation in Continuous Casting Slab: A Numerical Simulation Study

Metallurgical and Materials Transactions B - Solidified shell bulging is supposed to be the main reason for slab center segregation, while the influence of thermal shrinkage rarely has been...     

Preparation and properties of novel pH‐sensitive core−shell microspheres for enhanced oil recovery

A novel pH‐sensitive core?shell microsphere was synthesized by growing sodium acrylate as a shell on crosslinked polyacrylamide particles as the core by surface‐initiated atom transfer radical polymerization. The structures and characteristics of the microspheres were confirmed by Fourier transform infrared spectroscopy, ¹H NMR spectroscopy, SEM, transmission electron microscopy and AFM. The viscosity and size of the microspheres in response to changes in pH value were also investigated. As a kind of potential profile control and flooding agent, the performances of permeability reduction and enhanced oil recovery were studied in designed experiments. © 2017 Society of Chemical Industry     

Two photoluminescent polymers based on fluorene and 2,4,6‐triphenyl pyridine: Synthesis and electroluminescence

Two fluorene and triphenyl pyridine‐based linear and dendronized copolymers, P1 and P2 , were synthesized and fully characterized by ¹H‐NMR, ¹³C‐NMR, and matrix assistant laser desorption/ionization time‐of‐flight mass spectra, respectively. The absorption, photoluminescence (PL) behavior, and energy band gaps of P1 and P2 relative to those of polyfluorene end‐capped with benzene ( P0 ) were examined through UV–vis, photoluminescent spectra, and cyclic voltammetry. The UV–vis absorption and PL emission behavior of P0 and P1 were hardly affected by molecular architecture, while those of P2 were strongly correlated with the dendronized molecular frameworks. Cyclic voltammetry studies indicated the lower highest occupied molecular orbital energy level and wider band gap of P2 thin solid film relative to those of P0 and P1 . The new polymers were thermally stable up to 410°C. The better luminance and external quantum efficiencies of P1 relative to those of P0 in polymer light‐emitting diode (PLED) applications are due to improved electron injection, charge trapping and recombination at the pyridine sites. Through the experiments, it is found that the triphenyl pyridyl segments and excimers‐formation make pronounced contribution to long wavelength emission in P1 ‐based blue light‐emitting materials, and the analogous materials containing 2,4,6‐triphenyl pyridyl unit of P1 constitute highly attractive materials for white PLED applications. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

苏里格气田回注水污染防治措施

气田污水处理后回注地层是保证气田有效开发、防止污染的有效途径。文章介绍了苏里格气田在污水回注方面通过设计、施工、运行三个阶段所采取的选择安全回注地层、优化井身结构等各种防止污染措施,有力的保护了地下水资源。     

Comparison of Isolated Indentation and Grid Indentation Methods for HVOF Sprayed Cermets

This paper compares the results of two approaches of instrumented indentation for characterization of mechanical properties of HVOF coatings. Three types of HVOF sprayed coatings (Cr₃C₂-NiCr, WC-Co, (Ti, Mo)(C,N)-NiCo) were investigated by the means of isolated nanoindentation and grid indentation methods. The results of the isolated indentation revealed hardness and elastic modulus of the individual phases in very good agreement with the corresponding bulk material. The grid indentation method, based on statistical evaluation of a large number of indentations, was influenced by the carbide-matrix interface, which gave rise to a third peak apart from the two peaks corresponding to the carbides and metallic matrix. As a consequence, the bimodal Gaussian fit was insufficient and a trimodal fit had to be used. The results extracted from low load grid nanoindentations were quite close to the results of isolated indentations whereas higher load grid nanoindentation revealed overall properties of the coating.