关键词： 铁水预处理   机械搅拌法   脱硅   动力学   研究  

摘要： 在实验室进行了模拟铁水预处理机械搅拌法脱硅的动力学试验,考察了铁水温度、搅拌方法、初始硅含量、脱硅渣碱度等因素对脱硅反应速率的影响.试验表明：铁水温度对脱硅速率影响较小;机械搅拌可显著提高脱硅速率;脱硅反应初期的限制环节是硅在铁水侧的传质,当渣中FeO含量降低到一定程度后,FeO在渣相侧的传质成为脱硅过程的限制环节,或与硅在铁水侧的传质共同控制速度;脱硅渣碱度在0.32 ～0.65变化对脱硅速率无显著影响.

关键词： greenhouse cooling   fan ventilation   roof ventilators   combined ventilation  

摘要： The aim of this study was to analyse air exchange and temperature distribution in a greenhouse with combined mechanical and natural ventilation and to design more efficient mechanical ventilation *** this purpose,a computational fluid dynamics(CFD)model of the greenhouse was *** configurations were considered:Configuration 1(mechanical ventilation and closed roof ventilators),Configurations 2 and 3(mechanical ventilation and roof ventilators open 30%and 100%,respectively).After validation,the CFD model was used to improve the design of the greenhouse mechanical ventilation system in each of the three configurations *** greenhouse lengths,28 m,50 m,75 m and 100 m,were used in the *** to fan ventilation only,roof ventilation improved the climate of fan-ventilated greenhouses in terms of the air exchange rate(22%)and climate uniformity because the internal air was mixed better than with mechanical ventilation *** the greenhouse length increased,more advantages were achieved with natural ventilation compared to mechanical *** most configurations,there was a strong linear correlation between temperature gradient and greenhouse *** greenhouse whose regression line had the steepest slope was the one with closed roof *** the fan capacity produced a general reduction in temperature,but the effect was less intense for the greenhouses with open roof *** to box inlet ventilators,an enlarged continuous inlet in the wall opposite the fans increased overall system performance because it eliminated backflow recirculation zones,which are prone to produce high temperatures.

关键词： 真空机械手   运动学   牛顿-欧拉法   动力学仿真  

摘要： 根据FROG-LEG型真空机械手的结构特点,提出了其等效的串联结构运动学模型,并求出了运动学的正反解。将FROG-LEG型真空机械手动力学问题分为水平和垂直两个方向进行讨论,用牛顿-欧拉法求出了两个方向的动力学方程。最后利用MATLAB机器人工具箱对机械手的运动学和动力学特性进行了仿真实验。

关键词： 工程机械   产品   约翰迪尔   董事长   代表团   委员会  

摘要： 1976年，公司董事长威廉·休伊特（William Hewitt）率美中贸易全国委员会代表团首次访华，奠定了约翰迪尔在中国发展的基础。

关键词： 机械制造   转型升级   天津市   公司   有限   压力   纪实   加工企业  

摘要： 坐落于宝坻区朝霞街道工业区的天津宝洪源机械制造有限公司始建于1994年，当时仅为一家拥有两台车床的加工小作坊，经过一路摸索打拼，逐渐发展到今天的规模。作为一家科技型加工企业，宝洪源的产品涉及工程机械、船舶设备、风力发电设备、钢结构等领域，2013年公司销售收人超亿元。谈起企业的转型升级经历，企业负责人感慨万千。

关键词： Adenosine Triphosphate/metabolism   Hydrolysis   Kinesin/metabolism   Kinetics   Microtubules/metabolism   Models, Biological   Probability  

摘要： Motivation: Kinesin is a smart motor protein that steps processively forward and backward along microtubules (MTs). The mechanical kinetics of kinesin affecting its stepping behavior is not fully understood. Here, we propose a mathematical model to study the mechanical kinetics of forward and backward stepping of kinesin motor based on the four-state discrete stochastic model of the motor. Results: Results show that the probabilities of forward and backward stepping can be modeled using the mean probabilities of forward and backward kinetic transitions, respectively. We show that the backward stepping of kinesin motor starts when the probability of adenosine diphosphate (ADP) binding to the motor is much higher than that of adenosine triphosphate (ATP) binding. Furthermore, our results indicate that the backward stepping is related to both ATP hydrolysis and synthesis with rate limiting factor being ATP synthesis. Low rate of ATP synthesis under high backward loads above 10 pN is also suggested as a reason for the detachment of kinesin motor from MT in the kinetic state ***.P-i.

关键词： 动力机械   维护   保养   检查  

摘要： 我国的动力机械在不断的进步,不仅提高了生产效率,同样也适应了社会经济发展的趋势。但是有一些实际操作者缺乏对动力机械的维护和保养意识,在使用过程中出现大量的违规操作,大大减少了动力的使用寿命。本文重点对动力机械如何进行合理使用时应注意的事项进行了分析,并提出了对动力机械维护以及保养方面的几点体会。

关键词： 吸入性肺炎   急性呼吸窘迫综合征   机械通气   俯卧位通气   血流动力学   气道引流  

摘要： 目的探讨俯卧位机械通气对重症吸入性肺炎合并急性呼吸窘迫综合征(ARDS)患者氧合、血流动力学及气道痰液引流的影响。方法纳入2010年1月至2012年6月宿迁市钟吾医院ICU收治的28例严重吸入性肺炎合并ARDS患者,镇静、肌松、持续俯卧位通气状态下监测初始仰卧位、俯卧位1 h、俯卧位2 h、恢复仰卧位2 h各时间点的平均动脉压(MAP)、心率(HR)、中心静脉压(CVP)、脉搏血氧饱度(SpO2)、动脉血氧分压(PaO2)、二氧化碳分压(PaCO2),氧合指数(PaO2/FiO2)、痰液引流量等指标。结果与初始仰卧位比较,患者俯卧位1 h、俯卧位2 h时PaO2[(85±12)mm Hg和(97±10)mm Hg比(65±11)mm Hg]、PaO2/FiO2[(150±37)mm Hg和(158±50)mm Hg比(130±28)mm Hg]明显升高(P<0.05),且恢复仰卧位2 h时持续存在[PaO2(87±11)mm Hg,PaO2/FiO2(150±52)mm Hg,P<0.05],MAP、HR、CVP、SpO2差异无统计学意义(P>0.05)。俯卧位2 h时气道痰液引流量较初始仰卧位明显增加[(15.3±2.0)mL比(8.1±1.1)mL,P<0.05],而俯卧位1 h、恢复仰卧位2 h痰液引流量与初始仰卧位时比较差异无统计学意义[(9.1±1.0)mL和(8.3±1.2)mL比(8.1±1.1)mL,P>0.05]。结论俯卧位通气可改善严重吸入性肺炎合并ARDS患者的氧合,且恢复仰卧位后氧合改善持续存在;可改善气道痰液引流,但恢复仰卧位后改善引流作用消失;俯卧位通气对血流动力学无明显影响。俯卧位通气可用于严重吸入性肺炎并ARDS的辅助治疗,需气道充分引流的患者可适当延长俯卧位通气时间。

关键词： Mechanical alloying   Glassy powder   Crystallization   Thermal stability  

摘要： Al76Ni8Ti8Zr4Y4 glassy powder was produced by mechanical alloying process. The phase structure and the crystallization kinetics as well as the thermal stability were investigated using X-ray diffraction (XRD), transmission electron microscopy (TEM) and differential scanning calorimeter (DSC) in non-isothermal mode. The glassy alloy powder shows a distinct one-stage crystallization process with a wide supercooled liquid region. Crystallization occurs by the precipitation and growth of FCC-Al, with intermetallic compound AlTi, AlTi3, Al2Y and Al3Zr. The non-isothermal crystallization kinetics is analyzed by the modified Johnson-Mehl-Avrami (JMA) equation. The values of the Avrami exponent imply that the dominating crystallization mechanism of the present glassy powder is two- or three-dimensional nucleation and growth controlled by diffusion of atoms. The present glass powder has a large supercooled liquid region (SLR) Delta T-x value (86 K) and the apparent activation energy for crystallization is as high as 316 kJ/mol. The thermal stability was also evaluated by continuous transformation diagram (CHT) obtained by the extended Kissinger equation. To convince the thermal stability for a very long period of time, a quick annealing of the glassy powder at 700 K for 24 h was conducted and the related result was discussed. (C) 2013 Elsevier B.V. All rights reserved.

关键词： 农业机械总动力   预测   时间序列   ARIMA  

摘要： 运用黑龙江省1980-2011年的统计数据,建立了黑龙江省农业机械总动力的ARIMA模型,并进行了预测分析。结果表明:黑龙江省农业机械总动力是非平稳的时间序列,ARIMA模型的拟合效果良好;应用ARIMA(0,2,1)模型进行预测,1980-2011年预测值与实际值之间的平均相对误差为2.87%,可用于今后黑龙江省农业机械总动力的预测与分析。