科创中国

工业用线钳表面抛光机床是一种新型的磨削装置,其磨削过程用液压系统控制,从而实现大批量加工.该文首先利用三维设计软件UG NX3进行液压系统结构设计,再从结构方案的确定、主要部件的设计计算以及系统原理图的确定等几个方面对工业用线钳表面抛光机床液压系统进行了详细的分析,确保其性能良好.实验和应用证明:该液压系统运转平稳,稳定性和调节性能较好且密封可靠,使用效果良好.

Life-history theory predicts that in hibemators age of maturation is related positively to body size and negatively to the duration of active season aboveground. Yellow souslik is a large-sized ground squirrel with long hibernation, which suggests late maturation. We used four-year field observations of marked individuals to determine the age of maturation in males through analysis of age-dependent variation in body size, mass, androgen status, timing of spring emergence, ranging patterns and social behavior during the mating season. Yearling males were smaller, lighter, had lower level of fecal testosterone, emerged later and had smaller home ranges than older males. Social activity and the number of females encountered did not differ between age classes. After the second hibernation none of the studied parameters varied with age. Cluster analysis revealed two behavioral tactics: "active" males (adults only) emerged earlier, ranged more widely, initiated more contacts, encountered more females and were heavier than "passive" males (both yearling and adult). Thus, males of S. fulvus reached adult size and matured after two hibernations, which is relatively fast for such a big species with short active period. Indirect evidence for copulations and high variation among yearlings in all parameters suggest that some of them might successfully compete with adults. Active tactic of wandering and searching for females is energetically costly, and probably only adult males in good physical condition can afford it, whereas passive tactic of residing is energy saving and good for adults in poor condition and for yearlings that are continuing to grow.

日本某公司从1960年开始潜心研究PA透明树脂,相继成功研发高透明、低吸水性、尺寸稳定性的TR55和TR90树脂并推向市场.

Models of optimal escape strategy predict that animals should move away when the costs of fleeing (metabolic and opportunity costs) are outweighed by the costs of remaining. These theoretical models predict that more vulnerable individuals should be more reactive, moving away when an approaching threat is further away. We tested whether escape behaviour (includ- ing 'escape calling') ofLithobates sphenocephalus approached by a human was influenced by body size or the initial microhabi- tat that the individual was found in. Irrespective of their size, frogs in the open tended to remain immobile, enhancing their cryp- sis. Frogs in cover showed different responses according to their body size, but, contrary to our initial predictions, larger frogs showed greater responsiveness (longer flight initiation distance and distances fled) than small frogs. Small frogs tended to remain closer to water and escaped into water, while larger individuals were more likely to jump to terrestrial cover and call during escape. Density of frogs near the focal animal had no effect on escape behaviour. This study indicates a range of escape responses in this species and points to the importance of divergent escape choices for organisms which live on the edge of different environments .

根据超声波在混凝土介质中传播的声速、首波幅值、波形,分析了大尺寸混凝土试样的内部缺陷和均匀性,并对其弹性模量、衰减系数、松弛时间等动态参数进行求解.为了与超声波检测结果对比,采用改进的Hopkinson压杆技术对同配比的圆柱形混凝土试样进行实验研究来测定其相应动态参数,并对比分析了两种方法的不同之处.实验结果表明:两种方法测定的动态弹性模量基本一致;HPB试验测得的衰减系数比超声波试验测得的值大,这说明HPB试验中存在动态损伤的影响;HPB试验测得的松弛时间比超声波测得的增加了近一倍,这表明了在高应变率下,混凝土试样的脆性得到了明显的增加.试验数据可以为工程应用提供借鉴.

南京青奥会议中心(图1)建筑面积约40万m2,主体由46.9m高的6层会议中心、314m高的68层五星级酒店,和249.5m高的58层会议型酒店构成.两栋高层塔楼与会议中心在15m和21.12m通过空中走廊连通.青奥会议中心由扎哈·哈迪德设计,造型雕塑感很强,从高空俯瞰就好像一艘外太空的帆船.

全球领先的高性能信号处理解决方案供应商及病人护理行业的长期合作伙伴ADI公司,最近针对各类生命体征监护应用推出一款低功耗、单导联、心率监护仪模拟前端(AFE)AD8232.与竞争解决方案相比,AD8232AFE的尺寸缩小50%,功耗降低多达20%.凭借AD8232在功耗、尺寸和集成度方面的优势,设计人员能够开发用于重症监护之外的心率和心脏监护仪设备,例如个人健康管理和远程健康监护.

由隆巽教授率领的日本东京技术研究院在进行了为期5年的研究后于2012年3月20日宣布开发成功可提高产率、减少焦炭生成和延长催化剂寿命的石脑油裂解工艺.

新媒体改变新闻,电商牵手购物,金融进入互联网,跨界已经不再稀奇,同样,互联网和电视的融合也不是一天两天的事.如果说互联网时代的电视与电脑之争是客厅与书房的竞争,那么,电视面对移动互联网就是一场遭遇战了.先是各种互联网视频网站的出现让电脑屏幕吸引了越来越多的电脑控的眼球;再是越来越多的"盒子"让那些对电脑屏幕尺寸耿耿于怀的"骑墙派"转投互联网视频的怀抱.有统计显示,多屏趋势越来越明显,如在