火电厂汽机热力性能测试及分析研究

随着我国电力工业的飞速发展,火电机组装机容量也在不断增加。目前,火力发电厂普遍采用循环流化床锅炉和超超临界参数汽轮机。为了提高火力发电厂的经济效益,必须对发电设备进行优化设计、运行管理及维护保养等。本文首先针对当前火电厂汽机性能测试现状进行分析,对当前存在的问题,提出了一些优化策略,期望能为我国火电厂未来的发展提供帮助。

综合电子信息系统软件性能测试能力框架

为解决性能测试过程中分布在项目之间重复的软硬件资源、实现多项目跨区域协作、实现远程网络访问和集中化平台性能验证方案,该文提出了综合电子信息系统软件性能测试能力框架,阐述了该框架的架构和技术能力,展现了应用模式。该框架与实际项目相结合完成技能和最佳实践共享、跨团队资产共享、形成一致、可重用的流程,能最大化资源利用率,大幅提升测试效率,加快项目的发布进程,缩短项目周期,节约人力和测试工具成本。

水泥物理性能试验能力验证过程中的质量控制研究

在建筑工程中,水泥是建筑工程中必要的建筑材料之一。其中,水泥的质量和物理性质直接影响建筑工程的施工质量和施工安全。水泥物理性能试验能力验证过程必须要保证检验数据的准确性和真实性,才能保证质量的安全。

系统能力集成与开发的SCFP模型

基于能力的装备系统规划使装备系统的发展更好地适应未来战争。阐明了系统能力集成与开发的相关概念;在提出系统能力-功能-性能(SCFP)模型的基础上,研究了基于SCFP模型进行系统能力集成与开发的方法,该方法的核心是研究系统CFP各层次之间的映射关系;给出了系统能力集成与开发的一般过程,并以侦查卫星应用系统示例,简要说明了基于SCFP模型进行系统能力集成的实现过程。

Effect of benzoxazine resin on mechanical properties of nitrile rubber composites: Experiment and molecular simulation

Benzoxazine resin,being a new type of phenolic resin deve-loped to overcome the shortcomings of traditional phenolic resins,has been synthesized from phenol,formaldehyde and amine,and does not require solvent elimination or monomer purification to obtain a relatively clean precursor.It has potential application in the field of aerospace due to its low expansion coefficient,high weather resistance,high carbon yield,good mechanical strength,and excellent ablation resistance[1].It can be mixed with various other resins or polymers to produce new resins with a broad range of applications[2-3].

Characteristic and optimization of ferrite-rich sulfoaluminate-based composite cement suitable for cold region tunnels

To develop suitable grouting materials for water conveyance tunnels in cold regions,firstly,this study investigated the performance evolution of ferrite-rich sulfoaluminate-based composite cement(FSAC grouting material)at 20 and 3℃.The results show that low temperature only delays the strength development of FSAC grouting material within the first 3 d.Then,the effect of four typical early strength synergists on the early properties of FSAC grouting material was evaluated to optimize the early(£1 d)strength at 3℃.The most effective synergist,Ca(HCOO)_(2),which enhances the low-temperature early strength without compromising fluidity was selected based on strength and fluidity tests.Its micro-mechanism was analyzed by XRD,TG,and SEM methods.The results reveal that the most suitable dosage range is 0.3 wt%−0.5 wt%.Proper addition of Ca(HCOO)_(2)changed the crystal morphology of the hydration products,decreased the pore size and formed more compact hydration products by interlocking and overlapping.However,excessive addition of Ca(HCOO)_(2)inhibited the hydration reaction,resulting in a simple and loose structure of the hydration products.The research results have reference value for controlling surrounding rock deformation and preventing water and mud inrushes during the excavation in cold region tunnels.

能源储存技术在电动汽车领域的应用与发展前景分析

随着对环境问题的关注和对传统燃油车污染的担忧,电动汽车作为一种清洁能源替代品,受到了越来越多人的关注和青睐。能源储存技术是电动汽车的核心技术之一,它直接影响着电动汽车的续航里程、充电时间和安全性能。本文将对能源储存技术在电动汽车领域的应用与发展前景进行分析,重点讨论了电池技术、超级电容器、氢燃料电池等能源储存技术的应用状况和发展趋势。同时,本研究还探讨了能源储存技术在电动汽车领域的发展前景与挑战,包括市场增长趋势、政策支持、技术突破、环境可持续性和成本降低等方面。

Evolution of mechanical properties,localized corrosion resistance and microstructure of a high purity Al-Zn-Mg-Cu alloy during non-isothermal aging

The evolution of mechanical properties,localized corrosion resistance of a high purity Al-Zn-Mg-Cu alloy during non-isothermal aging(NIA)was investigated by hardness test,electrical conductivity test,tensile test,intergranular corrosion test,exfoliation corrosion test,slow strain rate tensile test and electrochemical test,and the mechanism has been discussed based on microstructure examination by optical microscopy,electron back scattered diffraction,scanning electron microscopy and scanning transmission electron microscopy.The NIA treatment includes a heating stage from 40℃to 180℃with a rate of 20℃/h and a cooling stage from 180℃to 40℃with a rate of 10℃/h.The results show that the hardness and strength increase rapidly during the heating stage of NIA since the increasing temperature favors the nucleation and the growth of strengthening precipitates and promotes the transformation of Guinier-Preston(GPI)zones toη'phase.During the cooling stage,the sizes ofη'phase increase with a little change in the number density,leading to a further slight increase of the hardness and strength.As NIA proceeds,the corroded morphology in the alloy changes from a layering feature to a wavy feature,the maximum corrosion depth decreases,and the reason has been analyzed based on the microstructural and microchemical feature of precipitates at grain boundaries and subgrain boundaries.

集群系统计算性能测试研究

为了研究一个具体集群系统的计算性能,文章利用2个Benchmark工具(NASparallelBenchmark,Linpack)测试一个拥有4个计算节点的集群系统的并行计算能力、高性能计算能力两个方面的性能。文章通过对比不同的系统软硬件配置和测试参数条件下的测试结果,对集群系统的总体计算效能做出了客观的评估,并对集群的优化提出了合理的建议。

蜡对钢丝绳润滑脂性能的影响

钢丝绳润滑脂通常用蜡作稠化剂(含量在15%以上),因此钢丝绳润滑脂的许多性能都取决于蜡的性质。从稠化性能,黏附能力,抗磨性能和抗氧化性能方面就80号微晶蜡,国产费托蜡,进口费托蜡,国产聚乙烯蜡和进口聚乙烯蜡对钢丝绳润滑脂性能的影响进行了考察。综合比较,选用国产聚乙烯蜡作为钢丝绳润滑脂的稠化剂。用国产聚乙烯蜡稠化150BS制备的钢丝绳润滑脂具有良好的黏附能力和抗磨性能,能够满足钢丝绳防护和润滑的要求。

钢骨混凝土构件的受力性能研究综述

本文基于对国内外钢骨混凝土结构的研究,介绍了钢骨的发展和特点,以及钢骨和混凝土的共同工作,梁、柱构件的斜截面和正截面的受力性能、刚度裂缝、抗震性能和其他相关的计算理论,介绍了适用于中国技术应用的梁力节点的力学性能以及彩色梁节点的试验研究,分析了钢骨混凝土施工技术在中国的应用。

Heat-treated wood and its development in Europe

Efficient use of timber is a vital concern problem, especially in these regions where the forestry coverage ratio is decreasing. Studies on physical modification of wood have been taken more attention due to the increasing attentions on environmental protection. Thermal modification is emphasized and developed quickly in developing countries, especially in European countries. A large number of researches have been conducted and some industrial production plants have been built. This paper reviewed the history of heat treatment, exemplifies the industrial developments in several European countries, summarized the basic principle of heat treatment and describes the environmental characteristics. The properties of heat-treated wood and its usage are also summed up.

Effects of thermal oxidation on microwave-absorbing and mechanical properties of SiC_f/SiC composites with PyC interphase

The SiCf/SiC composites containing PyC interphase were prepared by chemical vapor infiltration process. The influences of thermal oxidation on the complex permittivity and microwave absorption properties of Si Cf/Si C composites were investigated in the frequency range of 8.2-12.4 GHz. Both the real and imaginary parts of the complex permittivity decreased after thermal oxidation. The composites after 100 h thermal oxidation showed that reflection loss exceeded-10 d B in the frequency of 9.7-11.9 GHz and the minimum value was-11.4 d B at 11.0 GHz. The flexural strength of composites decreased but fracture behavior was improved obviously after thermal oxidation. These results indicate that the SiCf/SiC composites containing PyC interphase after thermal oxidation possess good microwave absorbing property and fracture behavior.

Effect of Nb addition on microstructure,mechanical properties and castability of β-type Ti-Mo alloys

To develop novel β-type biomedical titanium alloys,a series of Ti-15Mo-xNb alloys（x=0,5,10 and 15,mass fraction in%） were designed and prepared by using vacuum arc melting method.The present study focused on the effect of Nb addition on the microstructure,mechanical properties and castability of Ti-15 Mo alloy.Phase analysis and microstructure observation show that all the alloys consist of single β phase and the equiaxed β grain is refined with increasing Nb content.These β-type Ti-15Mo-xNb alloys exhibit good plasticity and rather low compression elastic modulus（in the range of 18.388-19.365 GPa）.After Nb addition,the compression yield strength of the alloys increases.With increasing Nb content,the micro-hardness of the alloys decreases.The alloys exhibit obvious fibrous strip microstructure after cold compression deformation.The castability test shows that the castability of the alloys after Nb addition decreases and that of the Ti-15 Mo alloy is the highest（92.01%）.

Effect of minor Fe addition on glass forming ability and mechanical properties of Zr_(55)Al_(10)Ni_5Cu_(30) bulk metallic glass

A series of rod samples with diameter of 3 mm（Zr0.55Al0.10Ni0.05Cu0.30）100-xFex（x=0,1,2,3,4） were prepared by magnetic suspend melting and copper mold suction casting method.The effects of a small amount of Fe on glass forming ability（GFA） and mechanical properties of Zr55Al10Ni5Cu30 bulk metallic glass（BMG） were investigated.The results show that the addition of an appropriate amount（less than 3%,mole fraction） of Fe enhances GFA,as indicated by the increase in the reduced glass transition temperature Trg（=Tg/Tl） and the parameter γ（=Tx/（Tg＋Tl）） with increasing Fe content,and GFA gets deteriorated by further Fe addition（4%）.The addition of Fe also effectively improves the compressive plasticity and increases the compressive fracture strength in these Zr-based BMGs.Compressive tests on BMG sample with 3 mm in diameter and 6 mm in length reveal work-hardening and a certain plastic strain in the alloy containing 2% Fe.The BMG composite containing 4% Fe also exhibits a high fracture strength along with significant plasticity.

Mechanical properties of monodirectional Gutou mortise-tenon joints of the traditional timber buildings in the Yangtze River region

The mechanical properties of the monodirectional Gutou mortise-tenon joints of the ancient Chinese traditional timber buildings in the Yangtze River region were studied using the experimental method. Three monodirectional Gutou mortise-tenon joints were designed according to the actual configurations. The failure modes,the hysteretic curves,the skeleton curves, the rotation rigidities, and the energy dissipation capacity of this type of mortise-tenon joints under the low cyclic reversed loading were obtained. The results show that the hysteretic curves of the monodirectional Gutou mortise-tenon joints appear to be Z shape and have obvious pinch effects. During the process of the test,these mortisetenon joints pass orderly through the elastic stage,the yield stage and the failure stage. The energy dissipation capacity of these mortise-tenon joints generally decreases with the increase in the rotation angle. The equivalent viscous damping coefficients of the monodirectional Gutou mortise-tenon joints are between 0. 161 and 0. 193. The results can provide the theoretical base for the computing analysis and repair design of Chinese traditional timber buildings in the Yangtze River region.

Elastic and thermodynamic properties of Re_2N at high pressure and high temperature

First principles calculations are preformed to systematically investigate the elastic and thermodynamic properties of Re2N at high pressure and high temperature. The Re2N exhibits a clear elastic anisotropy and the elastic constants C11 and C33 vary rapidly in comparison with the variations in C12, C13 and C44 at high pressure. In addition, bulk modulus B, elastic modulus E, and shear modulus Gas a function of crystal orientations for Re2N are also investigated for the first time. The tensile directional dependences of the elastic modulus obey the following trend： [0001] [1211] [1010] [1011]EEEE〉〉〉 . The shear moduli of Re2N within the （0001） basal plane are the smallest and greatly reduce the resistance of against large shear deformations. Based on the quasi-harmonic Debye model, the dependences of Debye temperature, Grüneisen parameter, heat capacity and thermal expansion coefficient on the temperature and pressure are explored in the whole pressure range from 0 to 50 GPa and temperature range from 0 to 1600 K.

Preparation and properties of novel Cu-based bulk metallic glasses Cu_(55-x)Zr_(37)Ti_8In_x

The glassy rods were successfully fabricated in the Cu-Zr-Ti-In alloy system by casting into a copper mold. The value of ATx reaches a maximum of 66 K for the BMG CusoZraTTi8In5 alloy. The reasons for enhancing glass forming ability of Cu-based BMGs with the addition of indium were discussed from atomic size and thermodynamics. Alternatively, the BMG Cu52Zra7Ti8In3 exhibits the highest compressive strength （1981 MPa） and the best plasticity among glassy Cu55-xZra7TisInx （x_〈5）. The total plastic deformation of Cu52Zr37TisIn3 before fracture approaches 1.2%.

Microstructure,mechanical properties and creep resistance of Mg-(8%-12%)Zn-(2%-6%) Al alloys

The microstructural characteristics, mechanical properties and creep resistance of Mg-（8%-12%） Zn-（2%-6%） A1 alloys were investigated to get a better overall understanding of these series alloys. The results indicate that the microstructure of the alloys ZA82, ZA102 and ZA122 with the mass ratio of Zn to A1 of 4-6 is mainly composed of a-Mg matrix and two different morphologies of precipitates （block τ-Mg32（Al, Zn）49 and dense lamellar ε-Mg51Zn20）, the alloys ZA84, ZA104 and ZA124 with the mass ratio of 2-3 contain α-Mg matrix and only block r phases, and the alloys ZA86, ZA106 and ZA126 with the mass ratio of 1-2 consist of a-Mg matrix, block r precipitates, lamellar Ф-Al2Mg5Zn2 eutectics and flocculent β-Mg17Al12 compounds. The alloys studied with the mass ratio of Zn to A1 of 2-3 exhibit high creep resistance, and the alloy ZA124 with the continuous network of r precipitating along grain boundaries shows the highest creep resistance.

Performance characterization, of rigid polyurethane foam with refined alkali lignin and modified alkali lignin

The two kinds of rigid polyurethane （PU） foams were prepared with respectively adding the refined alkali lignin and alkali lignin modified by 3-chloro-1,2-epoxypropane to be instead of 15% of the polyether glycol in weight. The indexes of mechanical performance, apparent density, thermal stability and aging resistance were separately tested for the prepared PU foams. The results show that the mechanical property, thermal insulation and thermal stability for PU foam with modified alkali lignin are excellent among two kinds of PU foams and control samples. The additions of the refined alkali lignin and modified alkali lignin to PU foam have little effect on the natural aging or heat aging resistance except for decreasing hot alkali resistance apparently. Additionally, the thermal conductivity of modified alkali lignin PU foam is lowest among two kinds of PU foams and control samples. The alkali lignin PU foam modified by 3-chloro-1,2-epoxypropane could be applied in the heat preservation field.