马钢直弧型板坯连铸机的设计

介绍了马钢 2 5 0 mm× 1 40 0 mm直弧型坯连铸机设计指导思想、连铸机主要技术性能指标、工艺流程、设备组成及采取的技术措施 :无氧化浇注 ,连续弯曲矫直 ,二冷区气雾冷却及自动控制 ,在线短定尺二次切割 ,对称式双向出坯 ,防止测量基准移位和台阶式对弧样板等。     

试样长度对 13CrMo44钢管力学性能的影响

研究了试样长度对13CrMo44珠光体耐热钢管力学性能的影响，研究结果表明，随着L0升高，该钢管的伸长率下降并满足δ=16.9% 68.2%√F/L0关系，L0较短时，其对钢管的抗拉强度（σb)和屈服强度（σs)没有什么影响；L0较长时，钢管的σb和σs都稍有下降，解释了产生上述现象的原因。     

用直接纺丝法制芳纶短纤维

研究了直接纺丝制取芳纶短纤维的新方法。讨论了纤维长度、直径及力学性能与纺丝条件的关系。发现影响纤维长度的主要因素是空气层高度和喷丝速度,影响纤维直径的主要因素为喷口直径及喷丝速度。此外,还用PPTA短纤维制成了均匀的PPTA"浆粕"纤维。     

墩头超长实用堰泄洪安全分析及模型试验验证——以缅甸DAPEIN(Ⅰ)水电站工程为例

以缅甸DAPEIN(Ⅰ)水电站工程为例,论述了将WES实用堰的闸墩墩头向上游超长延伸之后,对泄洪安全所造成的影响。针对WES实用堰流量系数、堰面动水压力容易受边界因子影响的特点,对设计断面的堰顶布置和墩头形状进行了优化。根据堰面空化数计算公式及水流特性推导出计算的关键部位,对空化数进行计算。采用几何比尺为1∶60的物理模型对溢流堰的泄流能力和堰面动水压力进行了试验测试。试验结果表明:溢流堰的模型试验泄流能力和设计泄流能力非常相近。堰面动水压力除工况2的B4测点出现了-1.2 k Pa的微小负压值外,其余堰面时均压强值均大于0。从而,在泄流能力和堰面动水压力两方面都验证了这种设计方案的合理性。该工程所遇到的结构布置问题在中低溢流坝工程中属常见问题,解决思路可为今后类似工程建设借鉴参考。     

路径长度受限的随机需求VRP的模型和算法

路径长度受限的随机需求VRP在生产、生活中有着广泛的应用。给出了路径长度受限的随机需求VRP问题的线性整数规划模型,在不允许部分服务和仅能服务失败一次的策略下设计了一个启发式算法。该算法以离散优化中广泛应用的扫描算法为基础生成服务的一个初始可行方案,然后利用模拟退火算法改进得到近似最优解。对需求为二项分布的50个结点、1个服务中心的问题进行了数值试验,数值结果表明该算法对求解路径长度受限的随机需求VRP是有效的。     

Interpretation of quasi-elastic light scattering data for flexible chains: model dependence

The autocorrelation functions and corresponding relaxation times obtained from the forward depolarized quasi-elastic light scattering experiment are exhibited for two quite similar models of flexible polymer chains in solution. A very small change in the chain dynamics is found to be sufficient to change the relaxation time from a relatively short time independent of chain length, with an autocorrelation function suggestive of an unweighted sum of contributions from all the relaxation times in the spectrum of chain motion, to a long time with an autocorrelation function identical with that for the end-to-end vector, strongly dependent upon chain length and dominated by the longest relaxation time in the spectrum. These results raise the question whether widely-used models in which information about short-range chain structure and motion is deliberately omitted can be expected to be appropriate for the interpretation of depolarized scattering experiments.     

A study of process monitoring based on inverse Gaussian distribution

The inverse Gaussian distribution has considerable applications in describing product life, employee service times, and so on. In this paper, the average run length (ARL) unbiased control charts, which monitor the shape and location parameters of the inverse Gaussian distribution respectively, are proposed when the in-control parameters are known. The effects of parameter estimation on the performance of the proposed control charts are also studied. An ARL-unbiased control chart for the shape parameter with the desired ${\mathit{ARL}}_0$, which takes the variability of the parameter estimate into account, is further developed. The performance of the proposed control charts is investigated in terms of the ARL and standard deviation of the run length. Finally, an example is used to illustrate the proposed control charts.     

射线探伤中环焊缝一次透照长度计算的探讨

通过对一次透照长度概念的分析以及对环焊缝内透偏心法(F相似文献   

科学管理确保乙烯装置长周期稳定运行

针对乙烯装置长周期运行面临的问题，中国石油独山子石化分公司乙烯厂采用科学的管理手段和技术进步措施，确保装置长周期运行。     

EXTERNAL FLUID HEATING OF A POROUS ED

This work deals with the thermal analysis of externally heated porous beds of finite length. A one dimensional model was developed that includes conduction and storage in both the fluid and bed, convective exchange between the fluid and bed, and the effect of adsorption/desorption in the bed. This model results in two coupled differential equations for the fluid and bed temperatures as functions of four independent dimensionless parameters. These equations were solved numerically using finite difference approximations. A truncation error analysis was carried out to maintain an accurate solution. The method of normalization is such that the results of this analysis are of use in bed design when the breakthrough characteristics in finite length beds are of interest. A method to measure bed thermal performance is defined and a means to optimize bed thermal performance is presented. An experiment was conducted to validate the numerically obtained results. A comparison of numerical to experimental results is presented