红壤与红壤性水稻土中磁性矿物特性的比较研究

用环境磁学方法研究了第四纪红土母质上发育的红壤和红性水稻土中磁性矿物的数量、粒度和类型。结果表明,红壤和红壤性水稻土的磁化率、频率磁化率、软剩磁、硬剩磁、非滞后剩磁和饱和等温剩磁等磁性参数有显著差异,磁化率的粒级分布表明,红壤性水稻土各粒级的磁性均受到破坏,以粘能降低最多,认为其磁性演变的主要机制是红 水稻土中超顺磁性和稳定单畴磁性颗的破坏。红壤性水稻土中基本不存在超顺磁性和稳定单畴态铁磁性矿物。     

本钢七号高炉水渣系统转鼓转速PID控制的应用

本文讨论了PID控制器的原理.并以转鼓转速控制系统为例,介绍了一个以PID控制器为基本调节单元的转鼓转速控制系统.同时讨论了转鼓转速的速度曲线以及PID参数的调整过程.     

斜壁桶形基础水平承载力的三维有限元分析

利用有限元软件ABAQUS对桶形基础受水平荷载进行数值模拟,并与模型试验结果进行对比.通过数值计算,分析饱和软黏土中单个斜壁桶形基础受水平荷载后的破坏模式.通过变动参数,分别探讨研究了土体有效重度、土体不排水抗剪强度、桶体等效长度和宽度、荷载作用高度对饱和软黏土中单个斜壁桶形基础水平承载力的影响及相对敏感性.     

船舶电力系统参数测量的应用和故障诊断

提出把船舶电力系统作为船舶发展过程中的一个重要组成部分来认识，描述了实际应用中占大多数的船舶电站的结构，并提及了船舶电网的特殊性，即其柔性功能及所存在的大量的扰动因素。文章着重讨论了参数测量的利用、诊断对船舶安全和船舶电力系统的有效运行所起的重要作用，指出了这些测量的特性，同时还提出了实现参数测量的进一步利用及用于故障诊断的基本设备和系统设想。笔者不仅叙述了上述内容在现阶段所取得的成就，而且还指出了其发展趋势。     

分数维稳定分布的参数估计

通过对参数估计问题进行研究以及稳定性定理和完整性的介绍,把稳定理论的参数估计推广到全族的分数维稳定性分布,由蒙特卡罗方法作出的检验表明所提供的估计量有很好的效率.     

Effects of continuous casting mould fluxes on reducing longitudinal and star cracks on a slab surface

1.IntroductionAstothecurrenttechnologyofcontinuouscastingofsteel,itisanemergencyformouldfluxestoharmonizetheconflictsbetweenheattransferandlubricationforslabcasting.Whenstructuralsteelwhosemassfractionofcarbonwcis0.09%to0.15%andhighstrengthlowalloysteel(HSLA)whosewcis0.14%to0.25%arecontinuouslycast,itisnecessarytocontroltheheatfluxfromtheslabshelltothecoppermouldnottoexceed1.7?06W/m2becauseofthebigandcoarseausteniticcrystalsintheinitialsolidifiedslabshell[1].Otherwise,longitudinalcrackstendt…     

热镀锌带钢抑制层的影响因素及控制要点

依据现有国内外热镀锌带钢理论研究和最新的实践研究成果,立足于冷轧热镀锌带钢工业化生产的实际情况,从带钢在退火炉中的运行速度、带钢入锌锅温度、锌液温度、退火炉露点、锌液Al含量五个方面阐述工业生产中热镀锌带钢抑制层的影响因素,梳理了抑制层的生长规律和控制要点,拟为热镀锌带钢的工业生产提供指导。     

机械加工切削用量选择的线图法

常规切削用量的选择方法是通过平时加工的经验积累,或通过查工艺手册的查表法来获得。本文通过对经验切削用量的整理、作图,用查图法来获得切削用量,改进了查表法比较麻烦,且查得的参数点比较少的缺点,为零件在进行机械加工时方便的、大范围获得切削用量提供了一种有用的、切实可行的方法     

Kinematic analysis of the shot-put: A method of assessing the mechanical work of the hand action force

The aims of this study were to (1) propose a method for evaluating shot-putters mechanical power, (2) investigate the relationship between mechanical work of hand action force (W_HAF), peak power output (PPO) of different limbs and shot-put performance and (3) show which of these two parameters (W_HAF, PPO) were the most appropriate to characterize the explosive abilities of the shot-putter. Twelve junior right-handed shot-putters, practised glide technique shot-put throwers (personal best?=?13.57 ± 1.72 m), participated in this study. Arm and leg force-velocity tests were performed to measure PPO. Kinematic analysis was conducted during a shot-putting event in regular conditions to quantify the W_HAF at the release moment and shot-put performance. Significant correlations were found between absolute arm and leg PPO with upper and lower muscle volumes (r?=?.67; p?=?.03; r?=?.76; p?=?.01; r?=?.74, p?=?.01; r?=?.65, p?=?.04). Positive relationships were recorded between absolute arm and leg PPO and shot-put performance (r?=?.67, p?=?.02; r?=?.81, p?=?.004, respectively). Shot-put performance was also closely related to the W_HAF (r?=?.93, p?=?.0001) and release velocity parameter (r?=?.86, p?=?.001). The present results confirm that force-velocity test and W_HAF constitute useful tools for assessing mechanical power in throwing. The W_HAF could be considered as more suitable than force-velocity test.     

Using Stated-Preference Questions to Investigate Variations in Willingness to Pay for Preserving Marble Monuments: Classic Heterogeneity, Random Parameters, and Mixture Models

This paper investigates heterogeneity in the preferences/WTP (willingness to pay) to preserve marble monuments in Washington, D.C. This is done in the context of three different discrete-choice random-utility models. The main focus is to estimate a mixture model of choices over preservation programs. This model captures the best features of random-parameters models and models that assume preference parameters are deterministic functions of observable characteristics of the individual. The mixture model, and it alone, predicts that increased preservation is a bad for a significant proportion of young, non-Caucasians. That some proportion of the population might consider preservation a bad is a contingency that should be planned for in efforts to value cultural resources. Data and computer code are available athttp://www.colorado.edu/economics/morey/dataset.html.