Ф426mm无缝钢管铣头倒棱机组的研制

介绍了中国重型机械研究院研制的国内第1套Ф426mm热轧无缝钢管铣头倒棱机组的主要技术参数、工艺流程、设备构成、主要结构特点等。该机组适合于加工Ф139．7～426．0mm×5～40mm、最大单重达4000kg的热轧无缝钢管；既可以倒去钢管端头锯切后的内外毛刺，又可将管端倒成任意角度的坡口并留钝边，或者平整钢管端面：已在国内投入使用。     

凸轮机构曲率半径的一种新的计算方法

凸轮机构的曲率半径是一个很重要的参数 ,计算公式很复杂。为了寻求一种更简便的计算方法 ,本文用运动分析的方法 ,推导了一种新的曲率半径的计算公式 ,为曲率半径的计算提供了一种新的方法     

齿轮倒棱工艺

通过对齿轮传动噪声产生原因的分析,介绍运用齿轮倒棱工艺,降低噪声的工艺方法及应用.     

钢管倒棱机夹紧装置设计研究

针对钢管在倒棱加工过程中,由于其长度及不直度的影响对夹紧装置的设计带来的困难,提出了采用固定夹紧和浮动夹紧相结合的夹紧方式,来解决钢管倒棱加工中的装夹难题.阐述了夹紧装置和新型浮动机构的设计原理和结构.研究结果表明,此夹紧装置能够避免钢管不直度的影响,提高钢管加工的质量.     

定子齿顶偏心对压缩机用IPMSM振动噪音的影响

采用分数槽集中绕组的内置式永磁同步电机(IPMSM)变频驱动的压缩机,其振动噪声有增长的趋势且存在许多新的特征。为此,本文基于定子绕组电动势和电流的谐波,建立径向和切向电磁力的等效表达式,用以分析该种电机振动噪音的产生机理;提出用定子齿顶偏心结构来抑制绕组电动势谐波,从而抑制振动噪声;用有限元法计算了该结构多个方案的电磁振动噪声,并进行了样机制作和实验,表明定子齿顶偏心可有效降低分数槽集中绕组IPMSM变频驱动压缩机某些关键频段的噪音。     

Tauschwirtschaft, Reputationsökonomie, Bürokratie

  Changing Economies. Exchange, Symbolic Capital and Bureaucracy in the Radium Market before the First World War The newly discovered radioactive substance radium was the most important research object in the early years of radioactivity research. It was very promising with regard to medicine and a notable curiosity. Radium, however, was not easy to get hold off - at least not in all times and places. This paper analyses the changing structure of the radium market up to 1914. During the first years, radium could be acquired only through personal relationships to those few researchers who were capable of producing it themselves. When the first chemical companies decided to begin radium production, radium could be bought (almost) like other commodities. This was not to last for long, however, since the Austrian government had already stopped exports of the pertinent raw material by 1904. The mineral was exploited by the Austrian academy of sciences, which distributed the radium obtained from it to those researchers who seemed the most deserving. When Austrian radium production increased, radium became a commodity again, albeit it was traded within highly monopolized structures. Radium’s astronomical price made the importance of a standard and reliable measurement procedures acutely felt and soon transformed the selling and buying of radium into a highly bureaucratized scientific procedure. These drastically changing conditions under which radium had to be obtained make clear that chemical substances, like instruments, have a history of their own.

     

Microencapsulation of phosphogypsum into a sulfur polymer matrix: physico-chemical and radiological characterization

The aim of this work is to prepare a new type of phosphogypsum-sulfur polymer cements (PG-SPC) to be utilised in the manufacture of building materials. Physico-chemical and radiological characterization was performed in phosphogypsum and phosphogypsum-sulfur polymer concretes and modeling of exhalation rates has been also carried out. An optimized mixture of the materials was obtained, the solidified material with optimal mixture (sulfur/phosphogypsum = 1:0.9, phosphogypsum dosage = 10-40 wt.%) results in highest strength (54-62 MPa) and low total porosity (2.8-6.8%). The activity concentration index (I) in the PG-SPC is lower than the reference value in the most international regulations and; therefore, these cements can be used without radiological restrictions in the manufacture of building materials. Under normal conditions of ventilation, the contribution to the expected radon indoor concentration in a standard room is below the international recommendations, so the building materials studied in this work can be applied to houses built up under normal ventilation conditions.Additionally, and taking into account that the PG is enriched in several natural radionuclides as ²²⁶Ra, the leaching experiments have demonstrated that environmental impact of the using of SPCs cements with PG is negligible.     

活塞环全自动倒角机的单片机控制系统设计

本文阐述了活塞环全自动倒角机工作原理,详细介绍了采用单片机构成的全自动倒角机电气控制系统的硬件、软件和可靠性的设计方案,给出了电气控制系统的硬件电路图、程序流程图。该控制系统实现了上下料、活塞环整形、活塞环压紧、活塞环倒角、空仓停车报警、故障报警等功能的自动控制,并实现了设备与上位计算机的通讯。     

考虑累积损伤的坞式船闸裂缝扩展及钢筋锚固改进研究

坞式船闸受力复杂,河侧闸墙倒角附近易开裂,钢筋锚固长度设计为现行水工行业规范最小值时,裂缝扩展路径可能绕过锚固延长段,甚至引发倒塌事故。采用扩展有限元方法(XFEM)建立仿真模型,研究考虑累积损伤下的坞式船闸裂缝扩展规律,并对钢筋锚固提出改进措施。结果表明:考虑累积损伤的钢筋混凝土闸室裂缝扩展路径,均在相同荷载作用下素混凝土状态闸室的拉应力区内部或附近;倒角附近钢筋锚固长度取规范最小长度时,部分损伤情形中荷载作用下裂缝扩展路径会绕过闸室倒角附近钢筋锚固延长段,导致结构极限承载能力无法满足要求;将钢筋锚固段延长,使穿出素混凝土状态闸室拉应力区的钢筋长度等于规范最小锚固长度,可使锚固延长段穿过裂缝扩展路径,并减小裂缝扩展长度和钢筋最大拉应力,使结构满足极限承载能力要求。研究结果可为船闸工程事故防治和相关设计规范进一步修订提供依据。     

人行过街设施的服务半径

为了分析人行过街设施的服务范围和服务能力,对人行过街设施的最大服务半径和服务半径进行研究.对道路上行人过街的延误与危险度进行分析,研究行人过街的心理特性与过街费用,提出人行过街设施最大服务半径的概念及计算方法,并以实例进行验证.通过对最大服务半径及行人过街心理及行为的分析得出人行过街设施服务半径的确定方法,提出可以用人行过街设施的服务半径来验证设施设置的合理性、确定行人过街路线的选择原则.可以提高人行过街设施设置的科学性及有效性.