新型建筑结构铝电解厂房的提出与分析

针对目前在我国常用的二层结构铝电解厂房的自然通风不适应大容量电解槽的现状。提出了新型建筑结构的铝电解厂房,并通过CFD模拟计算的方法,研究了该铝电解厂房形式的自然通风效果。分析了新型建筑结构的铝电解厂房的自然通风影响因素。     

铝电解厂房自然通风组织方式探讨

铝电解生产过程中产生大量的热，烟尘，经净化系统回收处理，厂房内仍存有乘余的高热量，烟尘及氟化氢气体需从厂房天窗排出室外，厂房的自然通风非常重要。总图布置，工艺流程布置，通风计算，建筑形式，相关专业共同配合，做好自然通风组织设计，达到良好的自然通风效果。     

铝电解厂房自然通风的现场测试分析

为获取自然通风的工业热厂房内的气流流动与温度分布的第一手资料，对某铝电解厂房的自然通风现状进行了现场实测。测试内容主要包括室外空气状态参数、排风温度、自然通风量、宝内温度分布和围护结构表面温度分布。测试蛄秉表明．具有双层结构的铝电解厂房下部进风窗的进风量仅占总进风量的36．6％。厂房迎风面进风窗的进风量远大干另一面的进风量．风压有可能形成进风窗排风的情况。从围护结构表面温度的测试结秉看，内表面温度均高于外表面温度．说明即使在一年最热的时间段内．铝电解厂房的传热方向仍然是由内向外。车间内空气温度和墙体表面温度均由下至上逐渐升高．说明自然通风下的工业热厂房具有明显的温度分层现象。     

浅析造气厂房附属砖砌体建筑温度裂缝产生的原因及设计控制

本文浅析了造气厂房附属砖砌体建筑因温度等原因产生的各种裂缝,通过有效的构造措施、设计控制,对其进行有效预防、控制。     

砖混结构抗震设计浅述

砌体结构是我国传统的建筑形式,在我国各类建筑中占有十分重要的位置。其中砖混结构在城乡建设中量大面广,又是人类活动和居住的主要场所之一,如住宅、办公、工业厂房及辅助用房等。     

现代设计理论和方法及其在锻压机械设计中的应用5 第五讲 结构优化设计(一)

前言在机械设计中,包括锻压机械的结构设计计算工作,长期以来基本上采用经验设计方法。这种方法通常是根据设计的原始条件及数据,参考同类型结构的技术资料,适当改变某些参数或从几种现有设计方案中挑选一种作为初始设计方案(根据设计任务的复杂性和设计人员的力量,初始设计方案可以是一个或数个)。然后进行结构的强度、刚度、稳定性等方面的分析与计算,必要时再配合以模型或样机试验。设计人员在分析计算结果或有关试验数据资料以后,认可或修改原始设计方案,再     

现代设计理论和方法及其在锻压机械设计中的应用6 第六讲 结构优化设计(二)

五、应用举例 (一)预应力多层筒体(模具)的优化设计近年来由于静液挤压相冷挤压技术的发展,对超高压挤压筒和凹模的承载能力提出了更高的要求,一般结构的筒体已无法承受,而预应力结构则可以极大地提高其承载能力。施加预应力的方法有两种:多层过盈配合年轮式和高强钢丝缠绕式(见图12和图13),前者已     

The use of experimental design method for the investigation of pitting potential of aluminum

The dependence of the pitting potential (E_p) of aluminum on chloride concentration, pH and the temperature of the solution was studied by the potentiodynamic method according to a statistical experimental design. The parameters of the statistical E_p model offered on the basis of Box‐Wilson experimental design method were evaluated with the use of the experimental data. Comparison of the predicted values from the model with the observed values showed that the model is a good fit. From the model equation the most noble E_p value of ? 420 mV was obtained when Cl^? ion concentration, temperature and pH of the solution were 57 ppm, 22°C, and 8.3 respectively. Box‐Wilson experimental design technique was proved to be applicable in modelling E_p of aluminum.     

Investigation on dual corrosion performance of magnesium-rich primer for aluminum alloys under salt spray test (ASTM B117) and natural exposure

Magnesium-rich primers perform very well on outdoor exposure and actual test conditions, yet fail rapidly in accelerated corrosion testing (salt spray test - ASTM B117). To investigate the behavioral dichotomy, Mg-rich primers exposed to salt spray testing and natural weathering were characterized at periodic intervals. The results revealed the presence of a thin and porous magnesium hydroxide layer in primers exposed to salt spray, and in natural exposure, a thicker, protective magnesium carbonate layer was detected and characterized. Samples exposed to atmospheric carbon dioxide exhibit excellent corrosion resistance but salt spray conditions are not conducive to facilitate magnesium carbonate formation.     

Effect of pre-aging pH on the formation of yttrium aluminum garnet powder (YAG) via the solid state reaction method

Yttrium aluminum garnet (YAG) powder was successfully synthesized by a novel solid state reaction method. The starting materials including: yttrium oxide (Y₂O₃), boehmite (AlOOH) and cerium chloride (CeCl₃·7H₂O) are pre-aged at pH 1, 2 and 3, respectively, before calcining. According to the experimental results, the case of pre-aging at pH 1 is the best condition for the formation of YAG powder. The particle size of Y₂O₃ and AlOOH are reduced by the pre-aging at pH 1. It induces to shorten the diffusion distance of the solid state reaction. The pre-aging at pH 1 process leads the formation of YAG powder via solid state reaction more easily. The emission intensity of the product was increased by the decrease of the pre-aging pH, the increase of the calcination temperature and the increase of the heating time.     

Al-Cu-Mg(2519)合金高温变形本构关系的神经网络模型

2519铝合金是一种新型的装甲材料。变形时,各热力学参数之间存在着非常复杂的非线性关系。本文采用Gleeble 1500热模拟机上圆柱体轴对称高温压缩试验数据建立了该合金本构关系神经网络模型。利用所建立的网络模型对其他一些热力学状态下材料的流变应力进行了预测,发现预测数据与实验数据吻合良好(总拟合度为2．6％),表明该本构关系神经网络模型有较高的预测精度。     

Kinetic speetrophotometric method for the determination of cerium（IV） with naphthol green B

A simple and sensitive spectrophotometric method was described for the determination of cerium(IV) based on its catalytic effect on the oxidation of naphthol green B by potassium periodate in the medium of sulfuric acid. The influences of acidity, concentration of reactants, reaction time, reaction temperature, and foreign ions were discussed, and the optimum reaction conditions were established. The reaction was monitored spectrophotometrically by measuring the decrease in absorbance of naphthol green B at 710 nm after a fixed time (8 min). The proposed method allowed the determination of cerium(IV) in the range of 0.08−2.4 μg·mL⁻¹ with good precision and accuracy, and the detection limit was 0.012 μg·mL⁻¹. The method was applied successfully for the determination of trace cerium in hair samples without previous separation. Recovery experiments were also performed, and the recovery was between 95.7%–111.0%.     

Ce(Au,Sb)2 with UHg2 structure type, a new member of the AlB2 family

A new ternary compound Ce(Au,Sb)₂, with a homogeneity range has been observed from X-ray powder diffraction of as cast alloys, a = 4.743–4.712 Å, c = 3.567–3.768 Å. Its crystal structure was investigated by X-ray diffraction from Ce(Au_1−xSb_x)₂ (x = 0.266) single crystal: CAD-4 automatic diffractometer, Mo K radiation, a = 4.7256(6) Å, c = 3.6711(6) Å, P6/mmm space group, V = 70.997(17) Å³, Z = 1, ρ = 10.732 Mg/m³, μ = 76.369 mm⁻¹, R₁ = 0.0415, wR₂ = 0.0793 for 99 reflections with I > 2σ(I₀). The coordination polyhedron of X (X = 0.734Au + 0.266Sb) atom is a full-capped trigonal prism [XCe₆X₃X₂]. Ce atom is coordinated by 14 atoms: [CeX₁₂Ce₂]. The compound is isotypic with UHg₂ structure, a deformation derivative of AlB₂ structure type. It forms isostructural compounds with La and Pr.     

Optimization of the pulsed current gas tungsten arc welding (PCGTAW) parameters for corrosion resistance of super duplex stainless steel (UNS S32760) welds using the Taguchi method

In the present work, a design of experiment (DOE) technique, the Taguchi method, has been used to optimize the pulsed current gas tungsten arc welding (PCGTAW) parameters for the corrosion resistance of super duplex stainless steel (UNS S32760) welds. A L₉ (3⁴) orthogonal array (OA) of Taguchi design which involves nine experiments for four parameters (pulse current, background current, % on time, pulse frequency) with three levels was used. Corrosion resistance in 3.5%NaCl solution was evaluated by anodic polarization tests at room temperature. Analysis of variance (ANOVA) is performed on the measured data and S/N (signal to noise) ratios. The higher the better response category was selected to obtain optimum conditions. The optimum conditions providing the highest pitting potential were estimated. The optimum conditions were found as the second level of pulse current (120 A), second level of background current (60 A), third level of % on time (80) and third level of pulse frequency (5 Hz). Under these conditions, pitting potential was predicted as 1.04 V_SCE that was very close to the observed value of 1.06 V_SCE. As a result of Taguchi analysis in this study, the pulse current was the most influencing parameter on the corrosion resistance and the background current had the next most significant effect. The percentage contributions of pulse current, background current, % on time, and pulse frequency to the corrosion resistance are 66.28%, 25.97%, 2.71% and 5.04%, respectively. Consequently, the Taguchi method was found to be promising technique to obtain the optimum conditions for such studies. Moreover, the experimental results obtained confirm the adequacy and effectiveness of this approach.