粉末金属压制过程建模方法(1)--金属塑性力学方法

介绍了建立描述粉末金属压制过程数学模型的难点．详细论述了目前4种主要的建模方法，分析、比较了各种方法的优劣，并对建模工作提出了展望和指导性意见。     

粉末金属压制过程建模方法(2)--广义塑性力学方法和内蕴时间方法

介绍了建立描述粉末金属压制过程数学模型的难点，详细论述了目前4种主要的建模方法，分析、比较了各种方法的优劣，并对建模工作提出了展望和指导性意见。     

Study of mechanical aspects of leak tightness in a pressure relief valve using advanced FE-analysis

This paper presents a numerical study involving the deformation of contact faces in the metal-to-metal seal in a typical pressure relief valve. The valve geometry is simplified to an axisymmetric problem, which comprises a simple geometry consisting of only 3 components. A cylindrical nozzle, which has a valve seat on top, contacts with a disk, which is preloaded by a compressed linear spring. All the components are made of AISI type 316N(L) steel defined using the multilinear kinematic hardening model based on monotonic and cyclic tests at 20° C. In-service observations show that there is a limited fluid leakage through the valve seat at operational pressures about 90% of the set pressure, which is caused by the fluid penetrating into surface asperities at the microscale. Nonlinear FEA in ANSYS using the fluid pressure penetration (FPP) technique revealed that there is a limited amount of fluid penetrating into gap, which is caused by the plastic deformation of the valve seat at the macroscale. Prediction of the fluid pressure distribution over the valve seat just before the valve lift is addressed in this study considering the FPP interaction on multiscale. This is the principal scope, since it allows adjustment of the valve spring force in order to improve the leak tightness.     

小弯曲半径管坯弯曲工艺探讨

此文阐述了对小弯曲半径管坯弯曲首先应进行工艺计算,如延伸率、强度计算等。然后选择合理工艺方案,以建立合理应力状态,提高材料塑性为目的。尤其应合理选择填充物。此文推荐采用低熔点合金作为填充物及全封闭挤压弯曲工艺。此文提供及推导了系列计算公式供计算工艺参数时参考。此文最后展望了小弯曲半径管坯弯曲工艺发展方向。     

粉末金属压制过程建模方法(3)--微观力学方法

介绍了建立描述粉末金属压制过程数学模型的难点，详细论述了目前4种主要的建模方法，分析、比较了各种方法的优劣，并对建模工作提出了展望和指导性意见。     

Testing the ability of males and females to respond to altered songs in the dueting green lacewing, Chrysoperla plorabunda (Neuroptera: Chrysopidae)

Green lacewings in the carnea group of Chrysoperla engage in species-specific heterosexual duets using low-frequency substrate-borne signals. Within each species, both sexes sing nearly identical songs. Songs are the principal barriers to hybridization between sympatric species in the complex. Here, we investigated the responsiveness of males and females of Chrysoperla plorabunda to synthesized, prerecorded songs that differed from the species mean in the period between repeated volleys of abdominal vibration. We tested 15–16 males and 15–16 females using playbacks of two signals that gradually increased or decreased in volley period, starting at the species mean. We found that (1) duets during courtship are accurate, interactive, and adjustable by each participant; (2) in staged duets, both sexes respond best to song tempos near the mean volley period of their population, but can nonetheless maintain duets with signals of nearly twice, or half, the normal volley period; (3) individuals fine-tune their adjustments to signals of different volley periods by changing their own volley duration and latent period, or less often by inserting extra volleys or skipping every other volley; (4) males are significantly better at matching signals of changing tempo than females; and (5) the range of song responsiveness of C. plorabunda does not overlap the natural range of volley periods found in Chrysoperla adamsi, an acoustically similar sibling species, thus reaffirming strong behavioral isolation. In sum, the precise, almost unbreakable heterosexual duets characteristic of song species of the carnea group result from tight mutual feedback between partners. Effective reproductive isolation between species can be based on song differences alone.     

生活污泥改性烧制超轻陶粒的研究

针对无机生活污泥的特性。选取了能够提高污泥可塑性的粘结剂和提高烧胀性的改性剂。通过塑性指数试验揭示了粘结剂对污泥塑性的改善程度,研究表明该粘结剂可在20％～60％的较大范围掺加都能改善污泥的塑性。正交试验揭示了在1200℃烧成温度时三种改性剂对污泥烧胀性的影响程度和规律．试验结果充分证明生活污泥经过改性可以烧制超轻陶粒。     

镶块锻模的可塑性设计

简要地介绍了镶块锻模结构特点和可塑性优化设计的难点,着重介绍扩大其使用性能可塑性设计方法的要点.     

Dispersal decisions and predispersal behavior in <Emphasis Type="Italic">Polistes</Emphasis> paper wasp ‘workers’

Social insects are popular models for studying the evolution of cooperation. Casteless taxa where individuals have the flexibility to either nest alone or cooperate are particularly valuable for understanding the causes and consequences of cooperative behavior. For example, some ‘workers’ from Polistes paper wasp nests disappear from their natal colony soon after pupal emergence and nest independently. However, little is known about dispersal behavior. In this paper, I compare predispersal behavior of wasps who leave their natal colony soon after emergence with behavior of individuals who remain on the natal colony as true workers. I found that P. dominulus females with short nest tenure behave much like gynes (reproductive-destined offspring produced at the end of the season), as wasps with short nest tenure are behaviorally selfish while on the natal colony. They spend a smaller proportion of their time foraging and a larger proportion of their time resting than workers with long nest tenure. In addition, I assessed the factors that may favor early dispersal. Nest environment strongly influenced dispersal; large colonies had a smaller proportion of females with short nest tenure. Queen turnover also increased dispersal behavior perhaps because queen turnover reduces relatedness between a colony’s current and future offspring, thereby reducing the kin-selected benefits of cooperation. Therefore, casteless social insects exhibit a surprising degree of reproductive flexibility. Individuals may use information about their internal state and nest environment to optimize their behavioral strategies.     

A stochastic weather generation model for Alaska

A specific problem encountered in ecosystem-level simulation of Arctic ecosystems is the depth and extent of the driving variable record. Often, climate records are of short duration, gathered at locations different from the area to be simulated, or do not contain all the variables required by a given model. This paper addresses this problem for ecosystem simulation in Alaska with the development of a weather generator. The generator, called WGENAL, is based on the WGEN climate generator developed and validated in the 48 conterminous states. Because of the extreme variability of weather in Alaska that is not accommodated by the statistical metrics in the earlier model, a new climate generator was developed. WGENAL generates daily values of precipitation, maximum temperature, minimum temperature, solar radiation, and wind run. Precipitation is generated using a Markov chain-gamma model. A two-parameter gamma distribution is used to generate wind run. Temperatures and solar radiation are generated using procedures developed in the earlier study. Validation of the generator shows it provides adequate diurnal and seasonal weather records for Fairbanks. Other comparisons of synthetic weather with observed weather for sites north of the Brooks Range in Alaska are also within the error of the original data.