The Mathematical Model of Cooling and Heat Transfer for the Solidification of Thin Slab during Continuous Casting Process

In the established model, the cooling differences are considered between the surface of inner radius and that of outer radius, and in the transverse direction of thin slab. And the conception for the effective coefficient of spraying water in continuous casting is firstly put forward. According to different casting speeds and different cooling zones, different time step lengths are adopted. In this model the heat transfer differences are thought over among vertical and curved zones, wide and narrow surfaces an well as angular zone of mould. The method of the corrected equivalent specific heat is used to deal with latent heat. The influence of forced convection is considered on heat transfer. Therefore, the model has higher accuracy and is consistent with the practice.     

Advance in Mathematic Model of Solidification Heat Transfer Process in Continuous Casting

The mathematic model of solidification heat transfer process in continuous casting strand is useful for quantitatively analyzing heat transfer in continuous casting process, quality control and process control. The heat transfer in continuous cast strand in crystallizer and secondary cooling zone have been analyzed. The attention has been paid to basic logic and methodology in model building up. Typical methods determing solution condition and parameters for the model have been discussed. Some numerical methods at the present time for solving solidification heat transfer model, such as finite difference method, finite-element method and boundary element, have been investigated comparatively. In the future, working on solidification heat transfer model, which is more practical, and the integration of the control model will play an important role in the development of high efficiency continuous casting technology.     

广西稻飞虱发生程度的气象预测预警

稻飞虱是影响广西水稻最严重的害虫,其发生发展与气象条件关系十分密切,为探索气象条件与稻飞虱发生程度的关系,进而开展稻飞虱发生程度的预测预警。笔者利用1991—2008年广西64个农业病虫测报站和对应县市的气象台站资料,对早稻稻飞虱发生等级与各项气象因子单因子做相关分析,找出具有生物学意义且指示性强的主要气象因子作为建模备选因子,采用逐步回归分析方法,构建早稻稻飞虱发生程度的预测预警模型,并对模型进行历史回代及2009—2012年的独立样本预测试报检验。结果表明：通过历史回代检验,早稻稻飞虱发生气象等级的模型与实测值达到基本一致,为89%;独立样本预测试报的模型预测检验结果达到基本一致以上,为75%,模型总体效果良好,其预测预警可为相关部门及时制定稻飞虱防控对策提供科学依据。     

The Changes of Underskined Interal Crack of Continuous Casting Billet During Piercing Process

This article studies on the distributional law of underskined internal crack in steel billets of continuous casting billet in additon to the appearance and features of the outer cross crack and outer fold which result from the internal crack during the piercing process.     

The Numerical Simulation Commercial Software for Secondary Cooling Process in Billet Continuous Casting

A numerical simulation commercial software has been developed by the object-oriented Visual Basic programming language on the basis of the 2D mathematical model of secondary cooling Process in billet continuous casting. Thereby an effective experimenting tool for computer simulation of continuous casting process is gained. By simulation with the software, the caster structures and operating parameters in continuous casting can be designed and optimized. The simulating calculation examples on several casters and its production applications indicate that the commercial software developed has more accuracy, practicability and commonality, as also as simpler operating capability. The simulated results have been successfully applied to the design and production of the high-efficiency modification for several billet casters interiorly.     

Computer Simulation for Analysing the Melting Action of Mould Powders During Continuous Casting

When analysing the performance of casting powders in a specific casting machine, the thickness of liquid slag is a very important parameter. If the liquid slag thickness is not kept above a certain minimum value during the continuous casting operation,the surface and internal quality of the cast products will be jeopardised because lubrication between the strand and the mould is impaired . It is necessary, therefore , to choose the appropriate type of mould powder .In the industrial experiments, it is very difficult and expensive to study this sensitivity by introducing controlled variation in one parameter while keeping all the other constant. Numerical and computer simulation methods are used in the study .They can predict the liquid slag thickness developed above the liquid steel and distribution of the temperature. The sensitivity of the liquid slag thickness to variations can be determined in the material properties of the mould powders.     

The Mathematic Model of H eat Transfer for the Solidification of Bille t D u ring Continuous Casting Process

In this paper according to different cooling feafures in the secondary coolingzone,a two-dimensional mathematic model of heat transfer is developed,which is suitable for the op-eration of the casfer in Chongqin g Special Steel Plant,In the model, a finite difference method isadopted and different boundary conditions a different time-step is firstly used.Thus the model isof high precision with a shorter calculation time.The optimum secondary cooling system of the con-tinuous billet can be gained by aimulating and optimizing calculations using the model.     

不同水分活度食品的货架期预测方法

快速准确地预测食品货架期已成为消费者、生产者和管理者共同关注的热点问题。而水分活度对于反映食品稳定性是个十分可靠的热力学指标,是快速预测食品货架期的关键因素。在分析和归纳国内外相关文献的基础上,根据食品品质变化机理及货架期预测理论阐述了水分活度≥0.8、0.5~0.8及≤0.5三个区间对食品品质的作用和影响,以确定货架期敏感性指标,同时归纳和总结了不同水分活度食品在实际运用中所采用的货架期预测模型。最后介绍了高光谱成像检测技术和基于生物阻抗的BP神经网络方法两种预测货架期的新技术,以期为食品的实时品质监控提供参考。     

Three-dimensional Random Damage Prediction Model of Concrete Caused by Freeze-thaw

In order to effectively assess the damage of concrete in freeze-thaw condition, prediction model for concrete frost damage is presented based on damage mechanical theory and the experimental test. The degeneration of tension strength of air-entraining concrete is tested after freezing and thawing. Provided with the fact that the degeneration of concrete is an interior damage evolving process, freezing and thawing damage accumulation of concrete is analyzed based on the discrete grid with probability of stochastic method. And Three-dimensional multi-parameters Weibull distribution model about concrete damage evolutions is presented. Parameters are estimated based on gradient method, and the mathematical model is verified according to the tested data. Corresponding algorithm is designed and programming is completed by C + + programming language to establish concrete durability prediction model under freeze-thaw conditions. It is indicated that the damage of concrete develops in nonlinear way as the freezing and thawing increases.     

云南烤烟填充值近红外光谱预测模型

为研究采用近红外光谱技术快速预测烤烟烟丝填充值的可行性,选取云南12个烤烟品种不同部位3个等级的140份烤烟初烤烟样品,采集样品近红外光谱和烟丝填充值,采用偏最小二乘法,利用100份样品近红外光谱和填充值建立近红外光谱填充值预测模型。用40份样品近红外光谱和填充值进行模型外部验证,对填充值测定值和预测值进行t检验,T＝0.4125,在显著性水平α＝0.05下,t(0.05,39)=1.6849,T     

基于ForcTT模型的开化县油菜花期预报

[目的]为及时向政府和游客提供准确的花期预报,指导乡村旅游活动,[方法]应用2004-2015年油菜生育期观测资料和地面气象观测资料,建立基于ForcTT模型的有效积温法则和逐步回归两种不同的预测模型。[结果]结果表明：基于ForcTT模型的有效积温法则有效避免了有效积温法则中各生育期不确定性的问题。两种预测模型得到的近三年普花期预测值结果相近,与实况值偏差略大,但能准确体现前后年的花期变化。经异地调查发现,积温模型更能体现花期在不同区域的时间差异。[结论]由此,基于ForcTT模型的有效积温法则可作为油菜花期预报的有效手段,为开展更有效的旅游气象服务提供技术支撑。     

水稻叶片伸长过程的模拟模型

水稻叶片生长过程的动态模拟, 对于实现水稻生长的数字化和可视化表达具有重要的理论意义和应用价值。本研究以4个不同株型的水稻品种为试验材料, 通过对水分试验、氮素试验条件下不同叶位叶片的叶长、叶宽特征进行连续观测, 综合分析了水稻叶片几何形态指标随生育进程和环境条件的变化规律, 进而构建了水稻叶片生长过程的动态模拟模型。模型采用Logistic方程描述了水稻主茎及分蘖叶片随生长度日(GDD)的动态伸长过程; 利用二次曲线描述了叶宽随GDD的动态变化过程; 分别用幂函数和一元二次方程描述了叶形(不同叶长处的叶宽)的动态变化过程; 另外, 以叶片氮素和水分因子分别描述了不同水氮水平对叶片形态建成过程的定量影响。同时利用独立的水稻田间试验资料对所建模型进行了测试和检验, 主茎和分蘖动态变化叶长、叶宽的均方根差(RMSE)分别为3.6 cm、3.96 cm以及3.15 cm、3.56 cm。表明本模型对水稻叶片的动态伸长过程具有较好的预测性和解释性。     

中国水稻稻纵卷叶螟区域气象等级预测模型

为了建立水稻不同区域、不同生育期的水稻稻纵卷叶螟预测模型,利用103个植保站2000-2014年稻纵卷叶螟虫情资料与气象资料,采用SPSS软件进行相关分析与主成分分析,在逐步回归的基础上建立水稻稻纵卷叶螟不同区域、不同生育期的发生发展气象等级与迁入气象等级预测模型。结果表明：以华南早稻为例,影响早稻移栽分蘖期发生发展的关键因子包括3月下旬累积降水量、4月上旬平均气温、4月下旬平均气温、5月上旬平均气温以及5月上旬最高气温＞30℃天数;迁飞的关键因子包括4月平均相对湿度、3月下旬平均气温、3月下旬平均相对湿度以及4月上旬平均日照时数。通过2000—2012年数据回代检验发现,不同水稻种植区移栽分蘖期和抽穗开花期发生发展气象等级平均准确率能达到80%以上,迁入气象等级在85%以上。通过2013—2014年外推预报时,发生发展气象等级平均准确率在80%以上,迁入气象等级在78%以上;当预测站点样本数较少时,预报的准确率普遍下降,西南一季稻下降明显。预测模型可从气象角度对中国水稻稻纵卷叶螟发生发展和迁入进行预测。     

Research of Failure Model and Life Prediction On Heater Tubes

An experimental research on the Alkylbenzene heater tubes material which has been operated for about 100 thousand hours is carried out. In addition, the corrosion product of heater tube has been examined by using an electronic probe and probe into the corrosion Mechanism of heater tubes. Based on the fault tree analysis on the heater tubes by using the FTA technology, the paper finds the main factors affecting the failure of the heater tubes, discusses the failure model of the heater tubes, put forward the mathematical mode of life prediction and failure model of the heater tubes.     

基于CA-Markov模型的甘州区土地利用变化预测分析

研究以张掖市甘州区为例,以黑河流域2000年和张掖市2007年土地利用/土地覆盖(LUCC)数据集的矢量数据、2014年Landsat 8 OLI_TIRS 8月份遥感影像和Google Earth影像为数据源,以Arc GIS10.1、ENVI 4.8和IDRISI 17.00为计算平台,利用CA-Markov模型对2014年土地利用变化进行模拟和预测,并将预测结果与2014年甘州区LUCC解译数据作对比分析,其Kappa系数为87.87%,表明预测与现实一致性较佳。最后对2021年甘州区土地利用分类进行模拟和预测。从预测结果可以看出:2000—2021年间甘州区耕地面积和建设用地面积呈现较快的增长趋势,未利用地面积呈现较快的减少趋势;林地和水域呈现缓慢地增长趋势;草地面积变化较小。简要分析了其变化原因主要归因于政策、社会经济、人口和科学技术几方面。对2021年甘州区土地利用变化的预测研究结果可为该区土地利用合理规划管理及经济发展政策的制定提供科学的决策依据。     

Validation Tests for Air Temperature Prediction Model STEVE: An Example of Guangzhou

STEVE（Screening Tool for Estate Environment Evaluation）is a statistical model through regression analysis. It can predict the air temperature by climate and urban morphology predictors for Singapore estate, while it hasn't been proved valid in other areas. Consequently, three groups of validation tests in Guangzhou area were conducted, one using the original data in the literature and the other two using experimental data from the field measurement. It is shown that STEVE tool can meet the engineering accuracy and can be used as a simple temperature prediction model tool in urban planning and design process in Guangzhou area and other cities with similar climate conditions. Besides, the STEVE tool can be optimized further to expand its applicable scope.     

基于马尔可夫模型的东北三省产业结构预测

为了合理规划东北三省产业结构,提升东北三省区域经济产业的整体竞争力,笔者应用马尔可夫预测方法对东北三省产业结构进行了研究,并用区间自适应遗传算法求解马尔可夫状态转移概率矩阵,依据2004—2014 年产业结构的统计数据,预测了东北三省第一、二、三产业结构,平均误差为2.92%,具有较高的预测精度。用该模型对2015—2016 年东北三省产业结构进行了预测,为东北三省制定相应的地方产业结构政策提供一定的理论依据。     

A Crop–Weather Model for Prediction of Rice (Oryza sativa L.) Yield Using an Empirical-Statistical Technique

Rice is the staple food in many countries and is grown in varied climates from per‐humid to semiarid areas. Crop–weather models were used to predict rice yield in India. However, in spite of a significant influence of solar radiation on rice yield, none of these models used solar radiation as one of the predictors. In this paper, an attempt was made to predict the first season (June–September) rice yield at Coimbatore, Tamil Nadu, India by including solar radiation as one of the predictors. Ten years (1987/88–1996/97) data were used for the study. Seven predictors viz., percentage of rice area during first season (X₁), number of days with minimum temperature below 22 °C in August and September (X₂), average daily maximum temperature for three months (July, August and September; X₃), average daily minimum temperature for three months (July, August and September; X₄), total of average sunshine hours in August and September (X₅), and total rainfall of July, August and September (X₆) total average solar radiation of August and September (X₇) were selected based on earlier report. Full model and stepwise regression analysis were performed using MSTAT computer package. The full model regression without solar radiation as predictor (Model I) recorded comparatively less R² (0.6292). Inclusion of solar radiation (Model II) enhanced the R² value considerably (R²=0.9464). Seven variables were further subjected to stepwise regression analysis and only four predictors were retained in the final model (Model III) with an R² value of 0.9234. The model III with minimum parameters Y=22119.5758 + 19.6898, X₁ ? 150.9261, X₂ ? 1126.7501, X₄ + 0.7179 X7 can be used to predict the first season rice yield (Y) at Coimbatore, India.     

用灰色系统GM（1，1）模型预测棉花生产

近年来由于自然灾害、比较效益等因素的影响，棉花生产出现较大波动，这种非线性变化给预测工作带来了困难。本预测对以往灰色系统ＧＭ（１，１）模型进行了二点改进：（１）利用高斯主元素消去法解算未知参数，在计算方法上是一大改进，同时提高了运算速度和计算精度；（２）加入了迭代计算。通过建立误差方程式，给定收敛条件和趋近次数，使模型的拟合精度提高。预测２０００年棉花面积将达到６２８万公顷，总产５７６．５６万吨，标准误差分别为７４．３８公顷和±８９．４４万吨。考虑到９０年代以来棉铃虫的危害，预测值加上标准差下限，就是未来较低水平下的棉花生产趋势。