Effect of Mild-calcined Coal Gangue Additionon Hot Strength and Refractoriness Under Loadof Ultra Low Cement Castablesin Al_2O_3-SiO_2 System

This work explored the way to improve hot modulus q/＇ rupture （HMOR） and refractoriness under load （RUL） by adding mild-calcined coal gangue （MCG） in Al2O3 -SiO2 ultra low cement （ULC） castables, making use of the in-situ effect of the MCG during heating-up. The influence of respective additions of 5%, 10% and 1.5% of the MCG powders calcined at 700℃ was investigated on HMOR at 1400 ℃ and RUL of the castables. With increased addition of the MCG, HMOR and RUL become significantly enhanced. At 10% of the MCG addition, HMOR reaches 3 MPa, as compared to 0. 3 MPa in the case of no MCG addition. RUL of the specimens dried at 110 ℃for 24 h can be increased by some 270 ℃ with 10% of the MCG addition. RUL 0.11 the specimens preheated at 1 500℃ for 3 h maintains the growth trend with the MCG addition increasing. The microstructure of the heated castable samples was investigated by means of SEM. The in-situ formed needle-like and interlaced mullite in the matrix is contributive to the tmprovement.

Preparation of Reference Samples for Refractoriness Under Load(Non-differential,with Rising Temperature) of Refractories

The preparation of reference samples for refractoriness under load （ non-differential, with rising temperature） of refractories was discussed. According to features and application of reference samples, quartz glass was chosen as a stand-by reference material for uniformity and stability tests. Then, the true value was fixed by gathering the testing results from many labs with stable testing levels and reliable testing results in China. The testing results from these labs were used for normality test by Shapiro-wilk method; and for abnormality value test by Grubbs method, for equal observation test by Cochran method. After confirming no abnormality values among the testing results from the labs. the average values of reference samples were calculated and the uncertainty was appraised. The results show that the standard value of reference samples is 1 386 ℃ and the expanded uncertainty is 12 ℃.

Effect of Thermal Cycling under Load on Martensite Transformation and Two-way Shape Memory Effect in a TiNi Alloy

The effect of thermal cycling under loading on martensitic transformation and two-way shape memory effect was investigated for Ti-49.8 at. pci Ni alloy. It is shown that Ms and Mf temperature increase with increasing the number of cycles, while As and Af temperature decrease during thermal cycling. The total strain et and permanent strain ep increase with increasing applied stress and number of cycles. The two-way shape memory effect can be improved by proper thermal cycling training under loading, while excessively high applied stress results in the deterioration of TWSME. The reason for the changes in martensitic transformation characteristics and two-way shape memory effect during thermal cycling under loading is discussed based on the analysis of microstructure by TEM observations.

Test Method for Refractoriness Under Load of Refractory Products(Non-differential,with Rising Temperature)

This standard specifies the definitions, theory, apparatus, specimens, procedures, test results and disposal, test error and report of test method for refractoriness under load of refractory products （non-differential, with rising temperature）.

An Efficient Framework for Utilizing Underloaded Servers in Compute Cloud

In cloud data centers,the consolidation of workload is one of the phases during which the available hosts are allocated tasks.This phenomenon ensures that the least possible number of hosts is used without compromise in meeting the Service Level Agreement(SLA).To consolidate the workloads,the hosts are segregated into three categories:normal hosts,under-loaded hosts,and over-loaded hosts based on their utilization.It is to be noted that the identification of an extensively used host or underloaded host is challenging to accomplish.Thresh-old values were proposed in the literature to detect this scenario.The current study aims to improve the existing methods that choose the underloaded hosts,get rid of Virtual Machines(VMs)from them,andfinally place them in some other hosts.The researcher proposes a Host Resource Utilization Aware(HRUAA)Algorithm to detect those underloaded and place its virtual machines on different hosts in a vibrant Cloud environment.The mechanism presented in this study is contrasted with existing mechanisms empirically.The results attained from the study estab-lish that numerous hosts can be shut down,while at the same time,the user's workload requirement can also be met.The proposed method is energy-efficient in workload consolidation,saves cost and time,and leverages active hosts.

Deformation and Spallation of Explosive Welded Steels under Gas Gun Shock Loading

We investigate deformation and spallation of explosive welded bi-steel plates under gas gun shock loading. Free surface histories are measured to obtain the Hugoniot elastic limit and spall strengths at different impact velocities.Pre-and post-shock microstructures are characterized with optical metallography, scanning electron microscopy,and electron backscatter diffraction. In addition, the Vickers hardness test is conducted. Explosive welding can result in a wavy steel/steel interface, an ultrafine grain region centered at the interface, and a neighboring high deformation region, accompanied by a hardness with the highest value at the interface. Additional shock compression induces a further increase in hardness, and shock-induced deformation occurs in the form of twinning and dislocation slip and depends on the local substructure. Spall damage nucleates and propagates along the ultrafine grain region, due to the initial cracks or weak interface bonding. Spall strengths of bimetal plates can be higher than its constituents. Plate impact offers a promising method for improving explosive welding.

Shape design of the reinforcement for bending load-carrying capacity of under-matched butt joint under four-point bending load

To improve the bending load-carrying capacity （ BLCC） of under-matched butt joint under four-point bending load in the elastic stage, the shape design of the reinforcement is studied based on the theoretics of mechanics of materials. The concept, criterion, realization condition and design proposal of equal bending load-carrying capacity （EBLCC） are put forward. The theoretical analysis results have been verified by the finite element method. The simulation results are coincident basically with the ones of theoretical analysis. The research results show that the shape design of the reinforcement of EBLCC can improve BLCC of under-matched butt joint and the unilateral-side type reinforcement can replace double-side symmetry

Novel Models and Algorithms of Load Balancing for Variable-structured Collaborative Simulation under HLA/RTI

High level architecture(HLA) is the open standard in the collaborative simulation field. Scholars have been paying close attention to theoretical research on and engineering applications of collaborative simulation based on HLA/RTI, which extends HLA in various aspects like functionality and efficiency. However, related study on the load balancing problem of HLA collaborative simulation is insufficient. Without load balancing, collaborative simulation under HLA/RTI may encounter performance reduction or even fatal errors. In this paper, load balancing is further divided into static problems and dynamic problems. A multi-objective model is established and the randomness of model parameters is taken into consideration for static load balancing, which makes the model more credible. The Monte Carlo based optimization algorithm(MCOA) is excogitated to gain static load balance. For dynamic load balancing, a new type of dynamic load balancing problem is put forward with regards to the variable-structured collaborative simulation under HLA/RTI. In order to minimize the influence against the running collaborative simulation, the ordinal optimization based algorithm(OOA) is devised to shorten the optimization time. Furthermore, the two algorithms are adopted in simulation experiments of different scenarios, which demonstrate their effectiveness and efficiency. An engineering experiment about collaborative simulation under HLA/RTI of high speed electricity multiple units(EMU) is also conducted to indentify credibility of the proposed models and supportive utility of MCOA and OOA to practical engineering systems. The proposed research ensures compatibility of traditional HLA, enhances the ability for assigning simulation loads onto computing units both statically and dynamically, improves the performance of collaborative simulation system and makes full use of the hardware resources.

基于截面增大法的扣放角钢焊接加固负载H型钢的轴压承载力研究

负载下焊接加固是既有结构加固的重要形式,然而当前对加固形式及加固效果的研究仍然较为缺乏.因此,提出了一种新型负载焊接加固构造,设计了8组扣放角钢焊接加固H型钢试验.研究了焊接过程中的截面应力重分布规律以及焊接加固H型钢柱的轴压力学性能.试验中加固构件的截面为加固前的1.53倍~1.55倍,焊接加固后构件极限承载增大为加固前的1.74倍~1.90倍;加固构件和原构件协同工作,获得了良好的加固效果,虽然焊接热输入降低了构件焊缝间隔处的屈曲应力,但负载加固的构件表现出相对零载加固构件更高的极限承载力.随后建立并验证了一种新型焊接加固H型钢柱的数值模拟方法,探究了不同截面面积加固构件的加固效果;揭示了不同焊缝间隔以及焊接热效应对加固构件极限承载力的影响,并建立了相应的设计方法.

负载下活性粉末混凝土钢筋网加固足尺混凝土柱轴压性能试验研究

为提高负载下钢筋混凝土(RC)柱的轴心抗压性能,使用活性粉末混凝土钢筋网(RPCSM)对负载下的RC足尺柱进行加固,设计制作了7根RC方柱试件,其中1根未加固对比柱、1根端部箍筋加密加固柱、2根RPCSM加固柱、3根端部箍筋加密RPCSM加固柱。考虑加固层厚度、钢筋网配筋率和端部箍筋加密对轴心受压RC柱性能的影响,进行了试验研究并分析了各试件的破坏模式、荷载-变形关系和应变变化规律。结果表明:加固柱的承载力提高了2.81~3.82倍;原混凝土柱与RPCSM加固层界面粘结可靠,共同工作良好;随着钢筋网配筋率的提高以及加固层厚度的增加,端部箍筋加密后整体性的提高,承载力和轴向变形能力提高,但延性有所下降。结合规范和破坏机理,给出了承载力计算公式,以促进该加固技术的推广。

新型等离子体点火技术在火电灵活性中的应用分析

近年来在国家政策的主导下,风电等新能源得到了快速发展,新能源的消纳问题也随之凸显出来,灵活性调峰是解决这一问题的有效措施。等离子体点火技术是一项卓有成效的低负荷稳燃措施,可满足深度调峰需求,有效提高火电机组对新能源发电的消纳能力。针对传统等离子体技术在火电灵活性应用中存在的问题,提出一种新型等离子体点火技术。该技术可使发生器阴极寿命提升至500 h以上,阳极寿命提升至1000 h以上;提高了煤质适应性,可适用于大部分燃用烟煤的电厂;而且点火过程中对燃烧器内燃强度有较好的控制,不易发生超温结焦现象。

基于ABAQUS的负载下碳纤维布受弯工字形钢梁有限元分析

随着软件有限元模拟技术和经济的不断发展,ABAQUS软件作为工程应用中大型有限元软件,经过有限元分析,均清晰地对问题进行了诠释。论文基于ABAQUS有限元软件,分析模拟研究了负载下,不同加固参数对加固受弯工字形钢梁力学性能的影响,为工程实际提供参考借鉴作用。具体结论主要为以下几点。不同负载水平(负载0%、30%、45%、60%、70%)的钢梁,加固参数相同,试件组合体承载力有限元模拟值与试验值误差在5%以内,吻合良好。负载水平不同,其最终破坏荷载也不尽相同,荷载挠度曲线规律相似,但负载水平的提高而破坏荷载有所下降。负载条件不同,不同加固层数下的荷载-挠度曲线近似相近,试件承载力与加固层数呈正比,但加固层数至一定程度,承载力增长幅度基本呈平稳趋势。当加固层数达到两层时,加固效果良好。随着改变碳纤维布长度,其荷载-挠度曲线规律基本相似,且随着碳纤维长度的增加,承载力也有一定提高。

Hot Load Deformation of Light-weight Insulating Fireclay Bricks

The hot load deformation tests of four kinds of insulating fireclay bricks were carried out using a high temperature creep furnace from Sinosteel Luoyang hlstitute of Refractories Reseorch Co. , Ltd. The testing load was fixed at 0. 069 MPa and the total testing time was with- in 6 h including the holding time of 1.5 h. The hot load defi〉rmation process of insulating fireclay bricks can be divided into three steps ： （ 1 ） expansion step from room temperature to RUL Tmax;（ 2 ） quick shrinkage step be- tween. RUL T and Ttest; 3 ） relatively slow shrinkage step during holding process. The deformation rate at the beginning of holding process （D0h） should be controlled withi, ＋0. 1%. The hot load deformation testing tem- perature of insulating fireclay bricks was optimized as the value of RUL T plus 220℃.

液体二氧化碳装置运行中存在问题与优化对策

液体二氧化碳装置以低温甲醇洗装置排放的高纯度二氧化碳尾气为原料气,通过脱除原料气中的水、硫化氢、羰基硫、氨气、甲醇等一些轻组分,把二氧化碳提纯到99.9%以上,气体经压缩、净化、液化,达到国家食品添加剂的标准后再制得高纯食品级液体二氧化碳。分析该装置运行中残气排放引发现场可燃气体及有毒有害气体报警仪报警、吸收剂粉化及压缩机低负荷运行时能耗损失等问题,挖掘节能降耗措施,优化生产运行参数,确保装置经济、安全、稳定运行。

高速动车组车下设备的吊耳动力学分析

为揭示CRH380AL高速动车组车下设备不同位置的吊耳产生裂纹差异很大的原因,开展实车运行工况下的振动和气动载荷测试,建立车下设备-车辆-轮轨-线路多重耦合大系统动力学模型,其中的车体和车下设备利用有限元法建立弹性体模型,轮轨子系统和转向架子系统使用多刚体动力学建模,轨道不平顺谱应用武汉至广州区间的实际测量数据,隧道通过和隧道交会等工况的气动载荷由八节车气动模型数值模拟获得,分析了车体弹性、气动载荷和螺栓刚度等因素对车下设备吊耳支反力的影响.研究表明:车下设备与车辆系统之间存在强烈的耦合行为,车下设备本身质量分布和车体弹性耦合效应导致4号吊耳垂向动态载荷最大,与现场故障裂纹占比最高的情况对应;气动载荷对车下设备8号吊耳动态载荷存在明显影响;低频区域的吊耳动态载荷随螺栓刚度的增大而增大,垂向平均动载荷和最大动载荷分别为其余2个方向的4倍和6倍.基于线路和车辆耦合的动力学分析方法可为车下设备动态力学行为的设计和疲劳性能的优化提供理论支撑.

偏心率对工字型CFRP-高强圆钢管高强混凝土短柱力学性能的影响

目的研究偏心率对内置工字型CFRP型材的高强圆钢管高强混凝土短柱力学性能的影响。方法利用ABAQUS有限元软件建立了工字型CFRP-高强圆钢管高强混凝土短柱模型,分析不同偏心率下构件的受力-变形关系、各材料分担荷载以及应力发展,探究混凝土强度、钢材屈服强度、含钢率和CFRP型材对组合柱力学性能的影响。结果随着偏心率的增大,构件延性提高,初始刚度与极限承载力降低,且降低幅度减小,偏心率与极限承载力呈非线性关系;偏心率越小,加入CFRP型材对组合柱承载力的提高越显著。结论偏心率越大,混凝土强度的利用率越低,钢管力学性能发挥越充分。偏心率小于0.328时,建议采用增大混凝土强度的方式增加构件极限承载力;偏心率大于0.328时,建议采取增大钢材屈服强度和含钢率的方式增加构件的极限承载力。

基于双馈风电机组频率响应解析模型的系统低频减载策略

规模化双馈风电机组主动参与系统频率响应对其动态和稳态特性均产生显著影响,然而,目前低频减载策略研究对该影响认识并不清晰且考虑不够充分。为此,提出了考虑双馈风电机组参与频率调节的电网低频减载策略和负荷切除决策模型。首先,根据与定子磁链定向的矢量控制方法,推导了双馈风电机组综合惯量控制的线性化解析模型。进而,分析并阐述了双馈风电机组综合惯量控制对低频减载切负荷量的影响,定量表征了双馈风电机组参加频率调节所抵消的部分功率缺额,进而确定了低频减载切负荷决策量。最后,通过算例证明,所提线性化解析模型能够准确刻画双馈风电机组的频率响应特性,且改进的低频减载策略能够在保证频率安全的前提下,减少切负荷量,充分验证了双馈风电机组参与频率响应的稳态功率支撑价值。

“薄壁圆筒弯扭组合变形”实验项目规范

为进一步提高材料力学实验教学质量,以薄壁圆筒弯扭组合变形实验项目为对象编写了实验项目规范,为工科实验力学教学做了有益的探索。

电力系统低频减载的单调控制特性

新能源占比的不断提高使得频率稳定问题日渐突出,因此迫切需要研究系统的频率稳定量化评估分析方法,也需对频率安全控制的最后一道防线低频减载进行更深入的分析。将单调控制系统理论运用到低频减载分析过程中,根据单调控制系统的输入-输出判定条件,推导单机和多机系统低频减载时频率分别需要满足的保序特性量化关系。此外,分析时采用全状态模型,在保证电网规律性和解析性的同时获得更高的可扩展性,综合频率与功角、电压以及相关参数间的耦合关系。并结合灵敏度分析了电网内部变量之间的相关关系,以指导电网故障时的参数设置。最后,分析目前光伏参与调频的3种常见情况,分别说明单调控制理论的适用性,并通过算例进行验证。