秦皇岛市某仓库三种火灾蔓延等级下火灾特性的数值模拟研究

火灾是危及人民生活的最频繁灾难之一,科学防火成为未来消防安全的重要方向.火灾发生时会产生大量的热,并同时释放对人体有害的燃烧产物.文中以秦皇岛市某仓库为例,使用流体动力学软件Fluent对中等、快速和极快三种火灾蔓延等级下火灾特性开展数值模拟.分析火灾发生后,温度场的分布特性和燃烧产物(CO、CO2)的流动特性,及其影...     

氨纶生产现状和市场分析

简述了氨纶的生产方法;概述了氨纶的世界市场发展现状和扩能动向,以及生产供需现状与预测;指出了加强新产品开发,提高氨纶产品质量,加强氨纶的上中下游厂家合作,扩大应用领域,拓展新的市场,使我国氨纶市场健康发展。     

自动化冲压线铝板料拆垛分张不良优化方法

自动化冲压线生产过程中,因铝板料没有磁性,板料在线首拆垛时存在分张不良现象,经现场调查研究,制定了控制板料残油、板料压窝、增加辅助分层装置等措施,解决了铝板料分张不良的问题。经生产验证,提出的方法有效,工艺合理,满足冲压线大批量生产的需求。     

Plate-like carbon-supported Fe_3C nanoparticles with superior electrochemical performance

Iron-based anodes for lithium-ion batteries(LIBs) with higher theoretical capacity,natural abundance and cheapness have received considerable attention,but they still suffer from the fast capacity fading.To address this issue,we report a facile synthesis of plate-like carbonsupported Fe3 C nanoparticles through chemical blowing/carbonization under calcination.The ultrafine Fe3 C nanoparticles are prone to be oxidized when exposing in air;thus,Fe3 C/C with mild oxidization and the fully oxidized product of Fe_2 O_3/C are successfully prepared by controlling the oxidization condition.When applied as an anode material in LIB,the Fe3 C/C electrode demonstrates excellent cycle stability(826 mAh·g~(-1) after 120 cycles under 500 mA·g~(-1)) and rate performance(410.6 mAh·g~(-1)under 2 A·g~(-1)),compared with the Fe_2 O_3/C counterpart.The enhanced electrochemical performance can be ascribed to the synergetic effect of the Fe3 C with mild oxidation and the unique hierarchical structure of plate-like carbon decorated with Fe_3 C catalyst.More importantly,this work may offer new approaches to synthesize other transition metal(e.g.,Co,Ni)-based anode material by replacing the precursor ingredient.     

Single-event effects induced by medium-energy protons in 28 nm system-on-chip

Single-event effects(SEEs) induced by medium-energy protons in a 28 nm system-on-chip(So C) were investigated at the China Institute of Atomic Energy. An on-chip memory block was irradiated with 90 MeV and70 MeV protons, respectively. Single-bit upset and multicell upset events were observed, and an uppermost number of nine upset cells were discovered in the 90 MeV proton irradiation test. The results indicate that the SEE sensitivities of the 28 nm SoC to the 90 MeV and 70 MeV protons were similar. Cosmic Ray Effects on Micro-Electronics Monte Carlo simulations were analyzed, and it demonstrates that protons can induce effects in a 28 nm SoC if their energies are greater than 1.4 MeV and that the lowest corresponding linear energy transfer was 0.142 MeV cm~2 mg~(-1). The similarities and discrepancies of the SEEs induced by the 90 MeV and 70 MeV protons were analyzed.     

Electrostatic-lenses position-sensitive TOF MCP detector for beam diagnostics and new scheme for mass measurements at HIAF

A foil–microchannel plate(MCP) detector,which uses electrostatic lenses and possesses both good position and timing resolutions, has been designed and simulated for beam diagnostics and mass measurements at the next-generation heavy-ion-beam facility HIAF in China. Characterized by low energy loss and good performances of timing and position measurements, it would be located at focal planes in fragment separator HFRS for position monitoring, beam turning, Bρ measurement, and trajectory reconstruction. Moreover, it will benefit the building-up of a magnetic-rigidity–energy-loss–time-offlight(Bρ-△E-TOF) method at HFRS for high-precision in-flight particle identification of radioactive isotope beams on an event-by-event basis. Most importantly, the detector can be utilized for in-ring TOF and position measurements,beam-line TOF measurements at two achromatic foci, and position measurements at a dispersive focus of HFRS, thus making it possible to use two complementary mass measurement methods [isochronous mass spectrometry at the storage ring SRing and magnetic-rigidity–time-of-flight(Bρ-TOF) at the beam-line HFRS] in one single experimental run.     

Effects of Optimized Operating Parameters on Combustion Characteristics and NO_x Emissions of a Burner based on Orthogonal Analysis

To optimize the structure of the burner,improve the combustion performance,and reduce the emission of NO_x,a self-circulating low NO_x combustion technology was used to design a new type of flue gas self-circulating low NO_x burner.Based on previous research on the numerical model of combustion and the composition of mixed gas on combustion and NO_x emissions,the effect of various factors on the ejection coefficient of the flue gas self-circulating structure was analyzed using the orthogonal test method,and the burner operating parameters,such as preheating temperature and excess air coefficient,were deeply studied through the three-dimensional finite element numerical model in this paper.The results show that the diameter ratio of the nozzle and the length of the cylindrical section of the flue gas self-circulating structure have great influence on its ejection and mixing ability.The optimal ejection coefficient was 0.4829.Overall,the amount of NO_x emissions greatly increased from 6.23×10~(-6) (volume fraction) at the preheating temperature 973 K to 3.5×10~(-3) at preheating temperature 1573 K.When the excess air coefficient decreased from 1.2 to 1,the maximum combustion temperature decreased from 2036.3 K to 1954.22 K,and the NO_x emissions decreased from 352.29×10~(-6) to 159.73×10~(-6).     

多相同步电动机中压变频调速装置系统集成

电力电子系统集成对于中大功率电力电子装置而言是要实现其系统结构和部件的标准化.作者以多相同步电动机中压变频调速装置为研究背景,探索了复杂大电力电子装置中的系统集成问题.作者对大电力电子装置进行模块化研究,首先分析如何选择主电路的一级标准模块,如三电平逆变单元的一级标准模块为一相NPC三电平桥臂;然后又分析了如何划分系统的二级标准模块,如整流模块、逆变模块、励磁模块等;随后作者又以多相同步电动机调速系统为例对控制系统进行分层研究,设计了各控制管理层的任务及各层问的信息流通信方式.利用这些研究成果,作者设计、制作了模块化的同步电机调速装置,试验取得了成功.     

Nanobridged rhombic antennas supporting both dipolar and high-order plasmonic modes with spatially superimposed hotspots in the mid-infrared

Mid-infrared antennas (MIRAs) support highly-efficient optical resonance in the infrared, enabling multiple applications, such as surface-enhanced infrared abso...     

一种商务车的整车噪声性能试验分析

试验测试一种商务车底盘系统及车厢内部的振动和噪声情况,并且分析该车底盘系统的振动和噪声对车厢内部座椅的影响,从整车的噪声和振动性能的设计角度为开发一种新型的高端商务车产品提供一定的设计依据.