Heat Transfer Characteristic of Molten Pool for Twin-Roll Strip Casting

Body-fitted coordinate transformation equation was deduced and used to generate the body-fitted grids of molten pool for twin-roll strip casting.The orthogonality of the grids on the boundary was modified by adjusting source item.The energy equation and the boundary conditions were transformed from physical space to computational space.The velocity field model proposed by Hirohiko Takuda was used to calculate the temperature field of molten steel,and the influence of technical factors was also discussed.

A simple simulator and method for measuring transient interfacial heat transfer in the strip casting process

This study presents a simple simulator for measuring the transient interfacial heat transfer between the molten steel and the copper casting roll for strip casting. The calculation principle of the heat flux is introduced in detail. Results show that the heat flux reaches the peak value of 9 MW/m^2 ,and decreases rapidly to 4 MW/m^2, and then fluctuates within the range of 2 MW/m^2 to 5 MW/m2. It agrees with the previous study. It also indicates the simulator can be effectively used to analyze the heat transfer during strip casting.

自动化剥锌设备极板自动接驳移载系统的设计

自动化剥锌设备极板自动接驳移载系统是湿法锌冶炼锌片自动剥离系统的关键设备,用于对输入和输出自动化剥锌设备的极板进行接收、存储、等间距排列、移载,实现极板在自动化剥锌设备与电解槽之间的转运。通过对自动化剥锌设备工作流程、现有结构、性能要求进行综合分析,对自动化剥锌设备极板自动接驳移载系统进行了设计,具体包括极板接驳装置、极板链条输送装置、极板放置装置、驱动系统、电气系统、控制系统等。现场应用表明,所设计的自动化剥锌设备极板自动接驳移载系统实现了极板在天车和自动化剥锌设备间的高效、稳定、快速转运,不需要人工辅助作业,为智能化无人剥锌打下了基础。

基于ASIC芯片的多探测单元设计与验证

以空间辐射环境中的粒子为研究目标,研制了用硅微条传感器作为探头、用集成芯片IDE3160进行信号处理的空间粒子探测系统.该系统采用两片硅微条传感器组成的硅微条探测阵列作为前端探头,并应用数字化的信号处理方法,获取空间粒子入射的位置及在硅微条内单位长度沉积的能量(线性能量传递,LET).从诱发单粒子效应的物理机制角度,对比重离子和脉冲激光在硅半导体中所产生物理效应的不同.采用1.064μm脉冲激光开展系统测试,获得良好的LET线性结果:该系统数据采集所需时间为2.47 ms,可探测到的LET阈值约为0.1MeV·cm^(2)·mg^(–1),皮尔逊相关系数(PCC)达0.998,表明系统测量结果与理论设计符合性良好.该系统动态范围宽、线性度好,具有较高的集成度、可拓展性及可移植性,可以搭载在各种空间探测卫星上.

焦化废水中氨氮吹脱传质速率的影响因素研究

焦化废水是一种常见的工业废水,它不仅成分复杂,而且还含有高浓度的氨氮和COD。生物处理系统能有效去除废水中的COD,但由于氨氮的抑制作用,通常会使生物处理系统的效能降低,因此需要采用适当的预处理方法去除废水中的氨氮。选用空气吹脱法对某焦化厂产生的废水进行预处理,重点考察了废水初始pH、通气速度和废水温度三个关键操作因素对废水中氨氮去除率和总传质系数的影响。实验结果表明,废水在pH为12.00、通气速度为0.5 m^(3)/(h·L)、废水温度为40℃和反应时间为240 min的最适条件下,氨氮去除率和总传质系数分别能达到88.74%和0.00846/min,处理后出水中氨氮的剩余浓度低于25 mg/L,该浓度已满足《炼焦化学工业污染物排放标准》(GB 16171—2012)中规定的氨氮的间接排放标准。

Improvement of Prediction Method for Strip Coiling Temperature

In order to improve the control precision of strip coiling temperature for hot strip mill,the BP neural network was combined with mathematical model to calculate convective heat-transfer coefficient of laminar flow cooling.The off-line calculated results indicate that the standard deviation of coiling temperature prediction is reduced by 22.84 % with the convective heat-transfer coefficient calculated by BP neural network.The prospects of this method for online application are bright.This method is more helpful to increasing the control precision of coiling temperature for hot strip steel.

岩棉条复合保温结构墙体传热系数研究

建筑墙体作为围护结构构件的主要组成部分,其传热系数的直接影响了建筑保温系统的隔热性能评价。检测机构在实验室内依照相关建筑节能检测标准对建筑构件和建筑材料的保温性能进行检测。通过实验室测量和数值模拟计算相结合,研究了聚氨酯板复合岩棉条保温墙体结构和石墨聚苯板复合岩棉条保温墙体结构的传热系数,结果表明:随着岩棉条宽度的增加,非匀质复合保温墙体的传热系数的计算值和测量值之间误差波动增大。当外墙墙体的传热系数设计值为不大于0.30 W/(m^(2)·K)、复合保温板的厚度为70 mm、岩棉条的宽度为20 mm、岩棉条所占面积比为0.09时,所测得的复合墙体的传热系数为0.31 W/(m^(2)·K),与计算设计值误差3.3%。

Study on Semi-Continuous Technology System for Soft Material Stripping in Large Surface Mines

Continuous and semi-continuous mining technology has become the main trend of modern surface mines in the world. According to the deposit characteristics of coal basin in China and Chinese situation,this paper discussed the new semi-continuous technology── shovel - transfer wagon-belt conveyor and its application prospect in large surface coal mines in China.

HEAT TRANSFER ANALYSIS DURING ROLLING OF THIN SLAB IN CSP

A mathematical model has been built to numerically predict the thermal history of thin slab during CSP （compact strip process） rolling. To estimate the temperature distribution in the slab mare accurately, the mathematical model combines heat transfer in the slab, in the roll, and at the roll-slab interface during bite. The numerical results agree with on-site running data, which proves the reliabili~, of the mathematical model. The results show that roll chilling has a significant effect on the temperature distribution in the slab.

Pretreating Stored Human Urine for Solar Evaporation by Low-Technology Ammonia Stripping

In order to avoid the loss of ammonia during solar drying of stored urine, low-tech stripping is suggested as a pretreatment process for ammonia recovery. The mass transfer of ammonia from stored urine with an initial pH of about 9 was tested in a simple closed vessel operated at 72°C, 74°C and 85°C. The specific urine/gas interface was 16.97 m-1. For ammonia absorption, a beaker with sulfuric acid was positioned in the gas phase of the container. After keeping the stored urine for 73 h at 85°C, the concentration of free ammonia (NH3) was reduced by more than 99%, and the pH of the stored urine decreased to 6.4 due to ammonia volatilization. Total ammonia (NH3+ NH4+) concentration was reduced by only 83% in the same period. At lower temperatures, the process was slower. Required treatment time can be reduced when specific gas/liquid interface is increased. Because it is known that water can be heated in solar boxes to temperatures above 90°C, this simple stripping apparatus is feasible to be operated with solar energy in remote areas with suitable climatic conditions where no electric power is available. As the area demand for solar “low-tech stripping” is less than 1 m2 per capita, this process can be looked at as a suitable pretreatment of stored urine prior to solar evaporation.

The key technologies of controlling low carbon steel as-cast strip surface quality

This article is try to explain or analyze the key technologies of controlling the surface quality of low carbon steel as cast strip through investigation of interface heat transfer between solidified shell and liquid steel.The one of the key technologies of controlling surface quality of low carbon steel as cast strip is through the casting roll surface texture in order to achieve the homogeneous solidification on the casting roll.Another is through forming a thin film on the casting roll surface in order to achieve a balance between rapid solidification and homogeneous solidification.This film formed between the twin roll and the molten steel can be controlled by adjusting the chemical composition and inclusion in liquid steel through controlling the amount of all[O]and free[O].

超重力技术处理高浓度氨氮废水的中试研究

针对传统吹脱法处理高浓度氨氮废水的不足,中试实验研究超重力技术的处理效果为在pH=13,温度40℃,气液比3 000,电机转数1 400 r/min的操作条件下,单级处理的脱氮率能达到80%多,说明超重力技术具有强化反应和传质过程的作用。此外,通过实验研究结果为工业化应用提供参考数据。

广义高阶有限条传递矩阵法

针对广义边界条件下的薄板屈曲问题,通过采用半解析广义高阶有限条法,结合传递矩阵法,推导出高阶有限条弹性刚度矩阵以及几何刚度矩阵,提出了矩形薄板屈曲分析的广义高阶有限条传递矩阵法。结合实例对提出的广义高阶有限条传递矩阵法和有限元法进行对比,分析了广义边界条件下矩形薄板的屈曲载荷因子与屈曲模态,发现两种方法的结果具有很好的一致性。同时,算例证明了广义高阶有限条传递矩阵法在单元数较少时计算结果也能与有限元法吻合较好,并且其计算精度比有限条传递矩阵法更高,证明了此方法可计算广义边界条件的矩形薄板屈曲问题。

水力喷射空气旋流器喷孔分布优化

为了进一步提高水力喷射空气旋流器(WSA)的传质性能,采用理论分析与实验相结合的方法,对其喷孔分布进行了优化研究。提出了基于同层相邻喷孔液相射流边界层相交于中心排气管表面的临界孔间距lc的概念及其计算方法,实验考察了喷孔排列方式和喷孔间距对WSA脱氨传质效果的影响。研究表明,在传质性能上,WSA的射流喷孔按正方形排列优于三角形排列;喷孔间距对脱氨传质效率有明显影响,存在一个较优取值,其值约等于1.28lc;从上往下到中心排气管出口处计算,侧壁开孔区长度应该占中心排气管长度的78%。研究结果为设计具有良好传质性能的WSA提供了依据。

锯齿翅片的传热与阻力性能试验

在风洞试验台上对16种不同结构参数的板翅换热器中使用锯齿翅片进行了传热和流动阻力性能试验，分析比较了翅片间距和翅片长度对其表面对流传热系数和空气阻力性能的影响。同时通过对16种翅片的244个试验数据点进行多元回归和F显著性检验，获得了j因子和f因子的经验关联式。在Re=5007500范围内，经验关联式的最大误差范围为±10％，绝对平均偏差分别为4．2％和5．3％。

吸附转移溶出伏安法测定氟罗沙星注射液含量

A new,simple and convenient method was proposed to determine FLRX.Cyclic voltammetric behavior of Fleroxacin(FLRX) on graphite electrode was studied.FLRX can be strongly adsorbed on graphite electrode.At the potential of +1.040V(vs.SCE),FLRX is oxidized and adsorbed on the electrode surface.Using HAc～NaAc as a buffer solution, FLRX showed a reduction wave and the peak potential of -0.110V(vs.SCE) by linear sweep voltammetry after the electrode was washed by double distilled water.A new method for the determination of FLRX was established by adsorptive transfer stripping voltammetry.The peak current is proportional to the concentration of fleroxacin in the range of 4～42 μ g/mL.The method is simple,sensitive,fairly free of interference and accurate.

济南恒隆广场深基坑斜撑支护体系分段先拆后撑施工技术

与水平支撑相比,深基坑斜撑支护体系具有工程量小、造价低、挖土方便、工期短等优点。以济南恒隆广场深基坑工程为例,介绍了斜撑支护体系分段先拆后撑施工技术。充分利用排桩斜撑支护体系的空间整体协同作用,合理确定分段拆撑长度;施工中先行分段拆除斜撑,然后分段施工地下结构,从而避免在地下结构上留洞,在发挥斜撑支护体系优势的同时,也克服了拆撑阶段对地下结构施工的不利影响。

基于水平圆管外加装排液板降膜流动的数值模拟

为了研究排液板对水平圆管外降膜流动与传热的影响,建立了水平圆管底部加装排液板的物理模型,采用流体体积函数(VOF)模型对其管外降膜流动进行了数值模拟,并将数值模拟结果与文献中的实验数据进行了对比.结果表明:加装排液板的水平圆管的平均液膜厚度比未加装排液板的水平圆管薄,管壁局部Nu大,排液板起到加速排液及减薄液膜的作用,有利于强化传热;排液板高度越大,管外同一周向角位置处的液膜厚度越薄,管壁局部Nu越大;排液板厚度较小或者较大都不能有效发挥加速排液的作用.

管内插入扭带的强化传热数值模拟

为了定性及定量研究管内插入扭带的强化传热方式,建立了以空气为传热介质的管内插入扭带强化传热的套管式换热器模型,进行数值模拟研究,并且与实验结果相比较,模拟值与实验值在Re>5000时的偏差小于2%,由此可验证数学模型的正确性。从插入扭带管和光滑管的速度与温度的对比图中可看出扭带的强化传热作用。并定量地描述出扭转比以及摩擦阻力系数与传热效果的数值关系。

GPU上两阶段负载调度问题的建模与近似算法

随着硬件功能的不断丰富和软件开发环境的逐渐成熟,GPU(graphics processing unit)越来越多地被应用到通用计算领域,并对诸多计算系统(尤其是嵌入式系统)性能的显著提升起到了至关重要的作用.在基于GPU的计算系统中,大规模并行负载同时进行数据传输和加载的情况时常发生,数据传输延时在系统性能全局最优化中变得不容忽视.综合考虑负载的传输时间和执行时间,以总负载makespan最小化作为系统性能的全局优化目标,研究了GPU上负载"传输-执行"联合调度问题.首先,将负载的时间信息和并行任务数与矩形域的二维空间联系起来,建立了负载的2D双层矩形域模型;然后,将GPU上负载调度问题归结为一类Strip-Packing问题;最后,基于贪婪策略给出了近似度为3的多项式时间近似算法,算法复杂度为O(nlogn).该近似算法的核心是对数据传输阶段进行负载排序调度.这从理论层面上证明了GPU系统采取"传输-执行"两阶段调度的有效性,即,在数据传输阶段采取负载排序调度,在负载执行阶段采取先来先服务(first-come-first-serve,简称FCFS)调度,能够使GPU性能达到全局最优或近似最优.