金属加工过程中应力状态的分析方法

分析简单地拉伸、压缩和扭转的情况时,应力状态能容易地被确定.但是,实际上在金属加工过程中材料是承受复杂的应力状态,在模具——工件接触面上增加有摩擦力.而且,这些应力和摩擦力一般地沿着接触面变化.准确的计算或预测载荷、力、应力和温度,不但对设计适宜的设备是重要的,而且对研究工艺期间材料的变化过程也是重要的.本文将讨论材料变形过程中所运用的主要分析方法及其优缺点.     

A study on the interactions among several plant secondary compounds and aphids

The research, focused on the specific interactions among seven plant secondary compounds and aphids, was carried out and the preliminary results showed: (1) "T-typed tube method" was regarded as the best method compared with others designed to observe the interactions. (2) Cabbage aphid was able to be attracted by laurolene while it was not susceptible to α-pinene, β-pinene and diamylene. (3) Gossypol, a major secondary substance in cotton, was able to be implicated as feeding attractant to cotton aphid. (4) Rutin might be implicated repellent to cotton aphid.     

Occurrence and congeners specific of poiychlorinated biphenyls in agricultural soils from Southern Jiangsu, China

A total of 198 agricultural soil samples were collected from Zhangjiagang and Changshu in Southern Jiangsu for analysis of 13 polychlorinated biphenyls (PCBs) in order to assess the levels of pollution, sources, area distribution, and potential risk for the environment. All methods were rigorously tested and an adequate quality control was ensured. Only one site had no PCBs residues, and the highest total PCBs concentration in the surface soils was 32.83 ng/g. The average concentration in all the soil samples was 4.13 ng/g, signaling low-level pollution. Tetra-, penta-, and hexa-chlorinated biphenyls were dominant species in soil samples, accounting for more than 75% ofΣPCBs in the soil samples. PCB118 was the most abundant congener in all the samples. The PCB118 was about 20% ofΣPCBs. The soil organic matter content showed only a weak correlation with the levels of all PCB congeners, in which a better correlation was noted for the more volatile lighter PCB congeners than for the heavier homologues. To a certain extent, the sources and land use seemed to influence the levels of PCBs.     

一种特殊形状制件的成形工艺

对弹匣前口板这种特殊形状制件成形工艺进行了讨论,找到了一种具有较高材料利用率,较高生产效率及简便易行的成形方法.     

ASM1中废水和污泥组分浓度的测定方法研究

对呼吸计量法应用于校准ASM1作了简明的阐述。在呼吸速率与模型组分关系的基础上,介绍了ASM1中废水与污泥各组分浓度的测定方法,并指出模型组分细化的意义。     

楔横轧轴肩的成形曲面的设计

此文分析在二辊楔横轧中轧制各类轴肩的过程。在假想工件轴端固定的图上确定楔侧面截面轮廓形状,再通过叠加轴向刚性移动量确定各截面实际位置,比较直观简便地设计出轧制轴肩的辊面上的成形曲面。最后归纳了设计步骤。     

后扣板冷挤压工艺及模具

此文分析了产品成形的特点,模具承载的负荷特点,从而在成形工艺上、润滑上、模具结构及选材上采取了相应的措施.用H-4水基高分子润滑剂和3Cr2W8V制作冷挤压模都取得了明显效果.     

江苏王港地区现代潮滩地貌发育特征

淤泥质潮滩是人类活动的强烈地带，江苏王港地区淤泥质潮滩宽广，由于人工引种大米草，滩涂围垦，大丰港的修筑，影响了王港地区原有潮滩发育的动力机制。王港地区生物分布和地貌特征具有明显的分带性。由于植被的促淤作用，王港地区潮滩南部垂向淤积速率较北部大；研究区内潮水沟的发育有两种类型。即泥滩带上的块体崩塌溯源侵蚀和零星分布的米草滩上的洞穴塌陷溯源侵蚀形成潮水沟；潮间带下部实测平均涨潮流流速小于平均落潮流流速，而涨潮平均含沙量大于落潮平均含沙量，潮间带下部潮水往复流及旋转流的作用在滩面上形成了双向波痕，陆地向海推进速度随着泥沙供给的减少以及滩面高程的降低而减慢。     

数值模拟的可视化及其实现技术

此文介绍了一个用于数值模拟过程的二维图形界面,它由两大部分组成:“MANU”实现计算结果的手工操作显示及编辑,“AUTO”用于数值计算过程的自动跟踪.文中详细介绍了系统的设计方法、结构、工作原理和主要功能.     

梯齿形桥梁伸缩缝U形弯曲件的成形技术

此文介绍一种新型桥梁伸缩缝关键零件U形弯曲件的成形技术.通过对该零件的变形分析和采用合理的工艺措施,使得这一成形难度较大的弯曲件一次压制获得成功.