合金成分与组织结构对铝合金阳极氧化的影响

本文叙述合金化元素、杂质元素及显微结构对铝合金阳极氧化的影响，介绍熔铸、热处理、加工成型及化学预处理等工艺参数对阳极氧化的作用。     

Static Behavior of a Historic Roof Structure

Historic roof structures of large monumental buildings are often complex with static behavior that is difficult to grasp. Yet, understanding their static behavior is necessary to adequately preserve and maintain them. The aim of this paper is twofold. The more general aim is to develop use of the finite element method in combination with visualization and to demonstrate its potential both for providing an understanding of historic structures and their static behavior and for supporting a dialogue regarding these matters. The more specific aim is to examine the static behavior of one particular roof structure and the damages to it that occurred. The roof structure selected was that of the medieval Swedish castle of Glimmingehus. A detailed computational model of the roof truss was developed, in terms of which a set of possible causes of the damages observed was simulated. Reliable causes were found and three-dimensional visualizations were carried out to demonstrate their respective influence on the overall structural behavior. As expected, use of visualization in the analysis was found to be very helpful for interpreting the relationship between the computational model and the computed results.     

Effect of Nonlinear Soil Behavior on Inelastic Seismic Response of a Structure

The characteristics of the earthquake motions at the base of a structure are affected by the properties of the underlying soil through the soil amplification and soil–structure interaction phenomena. In this paper the effect of nonlinear soil behavior on the elastic and inelastic response spectra of the motions that would be recorded at the free surface of a soft soil deposit or at the base of each structure is investigated. The analyses are conducted for a soil layer by itself and for a complete soil structure system using a finite element discretization of the soil in cylindrical coordinates and an approximate linear iterative procedure to simulate nonlinear behavior. Studies are conducted for structures, with a constant base and variable height modeled as equivalent linear or nonlinear single degree of freedom systems and an input motion at the base of the soil deposit representative of rock outcrop motions. Both mat and pile foundations are considered. The results illustrate clearly the importance of the nonlinear soil behavior.     

添加剂对Al-In-Ga-Pb合金阳极行为的影响

为改善铝阳极的性能,选用工业纯铝(99.8%),熔炼了Al-0.1 In-0.1 Ga-3Ph合金.在4 mol·L-1 KOH溶液中添加znO,KMnO4,Na2SnO3·4H2O,C4H4O6KNa4H2O,研究添加剂对合金阳极行为的影响.结果表明:溶液中添加znO后合金的析氢腐蚀得到明显的抑制,同时降低了合金的极化;KMnO4的加入可大幅提高合金的开路电位,但对抑制合金析氢腐蚀作用不明显;Na2SnO3·4H2O可提高合金的开路电位,降低极化.复合添加剂(11 mmol·L-1ZnO+0.61 mmol·L-1KMnO4)使合金开路电位负移,并有效抑制其析氢腐蚀,提高了阳极活性,综合性能较佳.     

Saturation and Preloading Effects on the Cyclic Behavior of Sand

In order to study pore water pressure response and liquefaction characteristics of sand, which has previously experienced liquefaction, two series of cyclic triaxial tests were run on medium dense sand specimens. In the first test series the influence of the soil saturation under undrained cyclic loading has been studied. It summarizes results of cyclic triaxial tests performed on Hostun-RF sand at various values of the Skempton’s pore-pressure coefficient. Analysis of experimental results gives valuable insights on the effect of soil saturation on sand response to undrained cyclic paths. In the second series of tests, the preloading influence on the resistance to the sands liquefaction has been realized on samples at various histories of loading. It was found that a large preloading induces a reduction of the resistance of sands to liquefaction.     

Peptide Effects on Social Behavior: Effects of Vasotocin and Isotocin on Social Approach Behavior in Male Goldfish (Carassius auratus).

The authors measured the effects of centrally infused peptides on social approach behaviors in goldfish (Carassius auratus), a social teleost. Vasotocin (VT) inhibited approach responses toward the visual stimuli of conspecifics in the absence of aggressive or sexual olfactory contextual cues in males, and a V1 receptor antagonist stimulated such responses, at least in males that were not highly social in baseline conditions, as did isotocin (IT). In the absence of social stimuli, VT did not affect activity, therefore indicating that the inhibition was not the result of nonspecific effects on arousal or motor functioning. These experiments indicate that VT and IT induce opposite effects on social approach responses in male goldfish and that endogenous VT, at least, is associated with levels of sociality. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of Cross Anisotropy on Three-Dimensional Behavior of Sand. II: Volume Change Behavior and Failure

The volume change behavior of cross-anisotropic sand is studied using results of a series of cubical triaxial tests. The relationships between the volumetric response, failure, and shear localization are addressed. Rates of dilation under various three-dimensional stress conditions are evaluated in conjunction with the peak shear resistance and initiation of shear banding in specimens of dense Santa Monica beach sand. The location of the line in principal stress space along which the tendency to deform changes from compressive to dilative (the characteristic line) is determined using two different methods. The uniqueness of this characteristic line for cross-anisotropic materials is analyzed.     

Structure and Catalytic Behavior of CuO-ZrO-CeO2 Mixed Oxides

The effect of doping CuO on the structure and properties of zirconia-ceria mixed oxide was studied. The results show that addition of CuO decreases the reduction temperature of ceria, and stabilizes the cubic structure of mixed oxides, and enhances catalytic activity of CuO-ZrO-CeO2 mixed oxides for CO oxidation. Increasing ceria content in the mixed oxides can enhance the catalytic activity, but some impurities such as sulfate make catalytic activity falling. There is little effect of calcination temperature on catalytic activities, implying that these catalysts are effective with good thermal stability.     

Effects of Placement Method on Geotechnical Behavior of Hydraulic Fill Sands

Results of an investigation of the geotechnical behavior of a hydraulic sand placed at a land reclamation site in Hong Kong are presented and interpreted. The study was conducted to aid in developing guidelines for quality control of hydraulic landfill placement. The work described consisted of: (1) field investigations; (2) static and cyclic triaxial testing; and (3) calibration chamber tests to study the cone penetration test versus Dr relationships for marine sands obtained from the reclamation sites. The results of this study clearly indicate that the placement technique is the single most important factor controlling the geotechnical behavior of a given type of sand when placed as a hydraulic fill. The weakest zone is generally located just beneath the water level where fill deposition is placed by pipeline discharge.     

Effects of Alcohol on Risk-Seeking Behavior: A Group-Level Analysis.

Although much drinking occurs in social settings, there has been little testing of alcohol in groups. The authors examined the effects of alcohol on performance on a group decision-making task. Fifty-four unacquainted male social drinkers were randomly assigned to 3-person groups that consumed either alcohol (0.82 g/kg) or a placebo. After drinking, participants decided whether to complete a 30-min questionnaire battery or toss a coin and, pending the outcome of that toss, complete either no questionnaires or a 60-min battery. Alcohol groups were significantly more likely than placebo groups to choose the coin toss. Results highlight the potent effects of alcohol on group decision making and suggest that application of social psychological theory and methods to the study of alcohol is warranted. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Austenite Stability Effects on Tensile Behavior of Manganese-Enriched-Austenite Transformation-Induced Plasticity Steel

Manganese enrichment of austenite during prolonged intercritical annealing was used to produce a family of transformation-induced plasticity (TRIP) steels with varying retained austenite contents. Cold-rolled 0.1C-7.1Mn steel was annealed at incremental temperatures between 848 K and 948 K (575 °C and 675 °C) for 1 week to enrich austenite in manganese. The resulting microstructures are comprised of varying fractions of intercritical ferrite, martensite, and retained austenite. Tensile behavior is dependent on annealing temperature and ranged from a low strain-hardening “flat” curve to high strength and ductility conditions that display positive strain hardening over a range of strain levels. The mechanical stability of austenite was measured using in-situ neutron diffraction and was shown to depend significantly on annealing temperature. Variations in austenite stability between annealing conditions help explain the observed strain hardening behaviors.     

Effects of Bed Structure on Erosion of Cohesive Sediments

Data from two recent papers are used to illustrate the effects of change of structure of fine sediment on erosion rates. The paper by Roberts et al. presents erosion rates as functions of bed bulk density and shear stress. Ranges of densities were obtained by allowing various times for consolidation, and the erosion tests were made where the density was nearly constant with depth. A marked change in the linear relation between erosion rate and density is presented that is attributed to a change of bed structure. The paper by Zreik et al. presents erosion rate data for a thin layer near the surface of a bed formed by sedimentation. The linear relation between amount of overburden removed and bed strength also has a marked change that can be attributed to a change of bed structure. The initial structures are described as aggregates of aggregates, and the changes are shown to be progressive collapse of the larger to smaller interaggregate pores due to thermal motion, biased by overburden pressure, to a nearly homogeneous primary aggregate structure. Small increases of bed stress above that necessary to initiate erosion of this structure have large effects.     

Social Regulatory Effects of Infant Nondistress Vocalization on Maternal Behavior.

This study investigated the social regulatory function of infant nondistress vocalization in modulating maternal response. Thirteen infants and their mothers were observed weekly in a face-to-face interaction situation from 4 to 24 weeks. After the occurrences and the speech quality of infant nondistress vocalization were identified, maternal contingent responses to these vocalizations were also coded. Each responsive action was further classified by the change processes involved. Results showed that it was the occurrence of infant nondistress vocalization rather than its speech quality that regulated maternal verbal response concurrently and that infant nondistress vocalization was more likely to be synchronized with maternal facial expression and touch than with head movements. Developmentally, significant individual differences were found in the linear growth patterns of overall maternal response and within the individual modalities when responding to speechlike vocalizations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of Silt on Three-Dimensional Stress–Strain Behavior of Loose Sand

An experimental study on the effects of nonplastic silt on the three-dimensional drained behavior of loose sand was performed employing a true triaxial testing apparatus. Laboratory experiments were performed on clean sand and on sand containing 20% nonplastic silt. The results indicate the failure stress levels and the overall trends of the stress–strain behavior were similar for both sands. However, the volume change behavior is significantly influenced by the presence of silt. The silty sand exhibited higher degrees of volumetric contraction during shearing than the clean sand. Relative density was used as the basis of comparison. The development of a shear band appears to have caused failure in all true triaxial testing performed, except in triaxial compression. This form of instability appears to increase its influence on the experimental results as the participation of intermediate principal stress increases. The formation of shear bands also appears to coincide with the cessation of contractive volumetric strain.     

组织缺陷对金属铍室温断裂行为的影响规律研究

利用扫描电镜(SEM)、透射电镜(TEM)和电子探针(EPMA)对比分析综合机械性能良好和零延伸率的金属铍材室温拉伸断口形貌和微观组织,研究金属铍室温断裂行为,并着重分析微观组织缺陷对金属铍室温断裂行为的影响规律。结果表明:金属铍室温拉伸断口形貌表现为准解理的断裂特征。解理裂纹形核后,裂纹扩展不受阻挡,表现为完全的脆性,因此铍材有限的延伸率主要来自于微裂纹形核阶段。铍材内部存在的杂质相汇聚区、片状晶体疏松和孔洞等组织缺陷,相当于在铍材内部预制一定尺寸的微裂纹,一旦微裂纹尖端形成,这类缺陷就会成为解理裂纹晶核,使铍本身的屈服过程不能发生,是降低铍材延伸率的主要原因;致密的大颗粒杂质相与基体失配、或在局部区域出现的粗晶粒与周围细晶粒不匹配,均易在铍材内部造成应力集中,也是降低铍材延伸率的原因。另外,当杂质相在晶界形成连续薄膜状晶界组织,导致铍材晶界结合强度降低,引起晶界断裂,造成铍材延伸率降低。     

Effects of Mo and Mn on Pitting Behavior of Duplex Stainless Steel

Effects of Mo and Mn elements on pitting corrosion resistance of lean duplex stainless steel in Cl-media solution have been studied.Gravimetric tests in 6 mass% FeCl_3 at 35 ℃ and potentiodynamic analysis in 3.5 mass% Na Cl were carried out.The corrosion potential( Ecoor) and the pitting potential( Epit) are shifted to a more noble potential because of the presence of Mo around the pits.While the presence of Mn could sharply reduce the value of pitting resistance equivalent number( PREn) and the pits can be formed more easily.The pits are found generating at the phase with a lower PREn.The identical tendencies between the Epitand PREn of weaker phase are the same.A corrosion mechanism has been proposed to determinate pitting corrosion behavior based on microstructural observations.     

Effects of Cross Anisotropy on Three-Dimensional Behavior of Sand. I: Stress–Strain Behavior and Shear Banding

The significance of material cross anisotropy in sands is underscored and experimentally evaluated in a series of true triaxial tests on Santa Monica beach sand in a cubical device. Failure patterns, initiation and development of shear banding, and complete stress–strain behavior are described for the entire range of the Lode angle under general three-dimensional loading conditions. Localized failure was found to govern the ultimate resistance of the sand for intermediate values of parameter b = (σ2?σ3)/(σ1?σ3) in each of the three sectors of the octahedral plane. Variations of the friction angle are fully described and show its significant dependence on the inherent cross-anisotropic material structure.     

Tempering of Martensite in Dual-Phase Steels and Its Effects on Softening Behavior

The isothermal and nonisothermal tempering of martensite in dual-phase (DP) steels was investigated mainly by analytical transmission electron microscopy, and the effect on softening behavior was studied. The isothermal tempering resulted in coarsening and spheroidization of cementite and complete recovery of laths. However, nonisothermal tempering manifested fine quasi-spherical intralath and platelike interlath cementite, decomposition of retained austenite, and partial recovery of laths. The distinct characteristic of nonisothermal tempering was primarily attributed to the synergistic effect of delay in cementite precipitation and insufficient time for diffusion of carbon due to rapid heating that delays the third stage of tempering. The finer size and platelike morphology of cementite coupled with partial recovery of lath resulted in reduced softening in nonisothermal tempering compared to severe softening in isothermal tempering due to large spheroidized cementite and complete recovery of lath substructure. The substitutional content of precipitated cementite in nonisothermal tempering was correlated to the richness of particular steel chemistry. Softening resistance during nonisothermal tempering was related to DP steel chemistry, i.e., Cr and Mn content. Fine cementite and less decomposed martensite in rich chemistry confer high resistance to softening compared to leaner chemistries, which indicated severe decomposition of martensite with coarser cementite.