开发电力经济运行系统 拓展锌电积过程节能途径

针对我国电力部门分时计价原则,根据由生产过程数据所建立的不同酸度下电流密度与电流效率间关系,建立锌电积过程分时供电能源优化模型。并将一种改进的遗传算法应用于分时供电能源模型,以获得最佳的分时供电方案以节约能源。     

基于成本分析的自发电负荷优化方法研究与应用

分析了钢铁企业用电成本的构成,指出高自供电率水平下,依据外购电电价不同区间,结合企业自发电生产的特点,分时调整自发电负荷,可以达到降低用电成本的目的,并介绍了该方法在钢铁厂实际生产过程中的应用情况。     

分时供电长周期锌电积实验经济性探讨

考虑到大工业用电分时计价,通过控制锌电积生产在用电峰时段、谷时段和平时段采用不同的电流密度组合,进行长周期锌电积试验,考察了分时供电对锌电积阴极锌质量、电流效率、直流电单耗及电费的影响。研究结果与工业生产实际进行对比分析,对于年产12万t锌锭的生产企业,在锌电积生产过程将节约电费支出上千万元,为锌冶炼企业带来较好的经济效益。     

变坟器有载开关故障原因浅析与预防

近几年来，因电业部门采取分时计价政策，我玫衽分时供电，帮此，变压器有载开关操作过度频繁，引起故障增多，故障的程度加重。本文论述了相起有载开关故障的主要原因和提出了预防措施。     

电弧炉工作点的最优化设计

通过对电弧炉供电参数的分析,建立了非线性最优化模型,计算电弧炉供电的最佳工作点。该模型可用于超高功率电弧炉,也可用于普通功率的电弧炉的化钢操作。     

韶钢120 t LF钢水温度预报模型的开发

以钢厂120 t LF精炼过程钢水、炉渣和合金为研究体系,以能量平衡机理模型为基础,建立精炼钢水温度预报模型。根据钢种、钢水质量和温度、目标出钢温度及处理时间、渣料和合金加入量及各种热损失所需投入的电能,确定精炼过程合理的供电曲线。并根据现场供电和工艺参数,预报钢水温度。20炉50RH1钢(%:0.48～0.50C、0.22～0.30Si、0.60～0.70Mn)测试结果表明,模型预报与实测钢水温度误差为±5℃。     

韶钢90tCONSTEEL电弧炉炼钢合理供电研究

根据现场实测数据,确定韶钢90tCONSTEEL电弧炉的非线性电抗模型和电气圆图,从而制定了较合理的供电曲线.文中着重讨论了建立电弧炉电抗模型的原则、方法及其对制定合理供电曲线的作用.     

韶钢90tCONSTEEL电弧炉炼钢合理供电研究

根据现场实测数据,确定了韶钢90tCONNSTEEL电弧炉的非线性电抗模型和电气圆图.从而制定了较合理的供电曲线.文中着重讨论了建立电弧炉电抗模型的原则、方法及其对制定合理供电曲线的作用和意义.     

高阻抗电弧炉合理供电技术研究

以石钢32 MV.A高阻抗电弧炉的生产实际为基础,采用PowerLogic2000电力参数线路监控仪对供电线路进行了实际测量,获得了高阻抗电弧炉炼钢生产过程中的电气运行参数。根据测量结果建立了石钢32 MV.A高阻抗电弧炉工作电抗模型。研制了电气特性图和工作点总表,研制出了新的供电曲线,在生产中已取代了原有供电曲线。生产运行结果表明,当铁水比为30%~60%时,新的供电曲线取得了吨钢电耗降低12~26 kW.h的节电效果。     

利用电价政策 降低生产成本

就供电部门对梅山现行的电价政策中的基本电价、分时电价、功率因数调整电价等进行分析，通过采取相应措施取得的效果，证明充分利用电价政策能减少电费支出降低生产成本。最后提出梅山应加强管理、科学用电、充分利用电价政策进一步降本增效的措施。     

A model for creep-fatigue interaction in terms of crack-tip stress relaxation

A model was developed to explain the mechanism of the degradation of fatigue lives caused by the growth of transgranular crack without cavitational damage in spite of the creep-fatigue loading condition for some type 304L stainless steel and 1Cr-Mo-V steel. The model was developed by incorporating the stress relaxation effect during tensile hold time into the pure fatigue crack growth model based on the crack-tip shearing process. In the crack-tip region, the stress relaxation during hold time at the tensile peak stress reduces the maximum stress level but accumulates inelastic strain, which induces creep crack growth during hold time and enhances subsequent fatigue crack growth during subsequent loading by promoting the crack-tip shearing process. The predicted creep-fatigue lives by the model were in good agreement with the actual lives for type 304L stainless steel at 823 and 865 K and for 1Cr-Mo-V rotor steel at 823 K. The model was further expanded to explain the degradation of the life under the conditions of compressive hold cycling for 1Cr-Mo-V and 12Cr-Mo-V steels.     

Finite-Element Analysis of Time Domain Reflectometry Cable-Grout-Soil Interaction

Three-dimensional finite element analysis is combined with field and laboratory measurement of time domain reflectometry (TDR) cable-grout response to analyze the interaction between the cable, grout, and surrounding soil mass during localized shearing. Finite element (FE) model parameters for the cable and cable-grout interface elements are back-calculated by matching results from laboratory shearing tests to FE calculated response. These parameters are employed in subsequent FE model geometries to model the behavior of TDR cable-grout composites in soft soils. Optimal grout and cable design is determined by analyzing the relationship between grout strength and stiffness and calculated cable shear stress.     

5500mm宽厚板生产线剪切模型应用

介绍了鞍钢5500 mm宽厚板生产线剪切线主要设备配置和剪切模型的基本结构及功能。剪切模型综合考虑了设备能力、钢板镰刀弯、剪刃间隙、钢板温度补偿等限制条件,能够精确计算钢板的切头尾量、轧制大板的宽度及长度。利用平面形状检测仪检测数据,通过剪切模型在线计算,实现了切头剪剪切位置的自动设定。     

Establishment of Optimal Blade Clearance of Stainless Steel Rolling-Cut Shear and Test of Shearing Force Parameters

 The purpose aims to improve the plate shearing section quality and metal yield by means of optimal blade clearance adjustment model of rolling-cut shear and accurate calculation of the maximum shearing force, as well as for the system optimization design, structure optimization design to provide important basis. A 3500 mm rolling shear of a large stainless steel factory was taken as the test object, and the blade clearance under different influence factors of the clearance value and the shearing section were tested. The optimized production accumulated data regression analysis and the rolling shear process of stainless steel shear test. The test results show that the optimal blade clearance adjustment module is a comprehensive function, which include steel plate thickness, material, temperature and shear plate volume. The shear stress at starting stage with the relative penetration depth increases affected by the above factors, and the fracture peak decreases rapidly after being cut into the roll phase constant.     

Interrelationship between the duration of HIV infection, viral load and CD4 positive lymphocyte count

BACKGROUND: The decline in CD4+ lymphocytes occurs at different rates in patients with HIV infection. A longer duration of HIV infection and a higher level of viral replication, represented by the viral load, are associated with a lower CD4+ lymphocyte count. However, the interelationship between these variables is still not well known. PATIENTS AND METHODS: 107 HIV-infected patients for whom the date of infection was known, were included in a transversal study, in which the CD4+ lymphocyte count and the plasma viral load were analysed, the last using an isothermal amplification method (NASBA). Patients were not receiving antiretroviral drugs or suffered intercurrent infections at the time of the study. RESULTS: The mean duration of HIV infection was 8.6 +/- 2.9 years. The mean CD4+ lymphocyte count was 366 +/- 264 x 10(6)/l. The mean plasma viraemia was 4.3 +/- 0.9 logs. In a linear regression model, the CD4+ lymphocyte count was explained in 21.7% of cases by the duration of HIV infection, meanwhile the viral load justified up to 36.2 of CD4+ cell variability. When both parameters were combined, up to 58.4% of CD4+ lymphocyte values were explained. In this model, changes of 1 log in viral load had a 4-fold higher effect on the CD4+ cell count than each year of HIV infection. CONCLUSIONS: The duration of HIV infection and, particularly the viral load strongly influences the current CD4+ lymphocyte count, although other variables should exist (virus with syncytium-inducing phenotype, age of the patient and his immunegenetic repertoire) influencing the different decline seen in CD4+ T-cells.     

宝钢厚板厂剪切线优化剪切模型的应用

概述了宝钢厚板厂剪切线的主要设备配置和优化剪切数学模型的控制功能,着重探讨了切头剪数学模型的实现条件和计算模式.宝钢厚板厂剪切线利用钢板平面形状检测仪(PSG)检测数据及轧制钢板中成品子板的分配计划,通过模型在线计算实现了切头剪剪切位置自动设定.模型综合考虑了设备限制、镰刀弯、钢板温度、钢板边部鼓肚量等限制条件,介绍了切头尾长度计算、轧制大板有效长度计算、分段粗切计算、来料超长或过短的处理方法等.     

Experimental Study on the Shearing Behavior of Saturated Silty Soils Based on Ring-Shear Tests

The shearing behavior of saturated silty soils has been examined extensively by performing undrained and partially drained (the upper drainage valve of the shear box was open during shearing) ring-shear tests on mixtures of a sandy silt with different loess contents. By performing tests at different initial void ratios, the shear behavior of these silty soils at different initial void ratios is presented and discussed. Undrained-shear-test results showed that the liquefaction phenomena in ring-shear tests were limited within the shear zone; for a given void ratio or interfine void ratio, both the peak and steady-state shear strengths decreased with increase of loess content. The partially drained shear tests revealed that a great reduction in the shear strength could result after the shear failure, due to the buildup of excess pore-water pressure within the shear zone; the magnitude of reduction in shear strength after failure was affected by the initial void ratio, the shear speed after failure, as well as the loess content in the sample. For a given void ratio or interfine void ratio, with increase of loess content, the drained peak shear strength became smaller, while the brittleness index became greater. It was also found that due to localized shearing, the permeability of the soil within the shear box after drained shearing could be three orders of magnitude smaller than before shearing.     

双螺旋搅拌法制浆工艺参数对AZ91D合金半固态组织的影响

双螺旋搅拌工艺制备了AZ91D合金半固态浆料,获得金属半固态加工要求的细小、等轴分布均匀的非枝晶组织。研究了熔体温度、搅拌速度和剪切时间对该组织的影响规律。结果表明:采用合适的搅拌工艺,可获得金属半固态加工要求的细小、等轴分布均匀的非枝晶组织。即降低降体温度、搅拌速度及适当剪切时间有利于细小球形晶粒的形成。加大搅拌速度及合理搅拌时间可以细化晶粒,主要是由于是高剪切作用下熔体获得一个非常均匀温度场,从而增加有效形核的缘故。     

Finite Element Method Analysis of Effect of Blade Clearance on Plate Shearing Process

 Blade clearance is an important technical parameter of the shear, which determines the shear quality of plate. The finite element method was used to simulate shearing process which is in the different specifications and blade clearances, and the impact on blade section and shearing force of blade clearance was analyzed. Comparing with traditional experience formulas and measured values, the limitations of the experience formulas were proved. And by contrasting with the shearing force data collected from Linfen Iron and Steel Company, the reliability of the finite element method was further proved. The simulated results show that the simulated values controlled by ductile fracture criterion and measured values are very close, and the deviation value is in the range of 4.8%-20.8%. For the same steel, if the plate is thicker, the blade clearance will be greater, and thickness and blade clearance are approximately linear. The difference between numerical simulation of the maximum shearing force and the measured results is 7.7% to 12.0%, and the simulation results are close to facts. With the increase of blade clearance and the thickness, the shearing force was increased to some degree.